Merge branch 'master' into next

[i3/i3] / src / con.c

#undef I3__FILE__
#define I3__FILE__ "con.c"
/*
 * vim:ts=4:sw=4:expandtab
 *
 * i3 - an improved dynamic tiling window manager
 * © 2009-2011 Michael Stapelberg and contributors (see also: LICENSE)
 *
 * con.c: Functions which deal with containers directly (creating containers,
 *        searching containers, getting specific properties from containers,
 *        …).
 *
 */
#include "all.h"

char *colors[] = {
    "#ff0000",
    "#00FF00",
    "#0000FF",
    "#ff00ff",
    "#00ffff",
    "#ffff00",
    "#aa0000",
    "#00aa00",
    "#0000aa",
    "#aa00aa"
};

static void con_on_remove_child(Con *con);

/*
 * force parent split containers to be redrawn
 *
 */
static void con_force_split_parents_redraw(Con *con) {
    Con *parent = con;

    while (parent && parent->type != CT_WORKSPACE && parent->type != CT_DOCKAREA) {
        if (!con_is_leaf(parent))
            FREE(parent->deco_render_params);
        parent = parent->parent;
    }
}

/*
 * Create a new container (and attach it to the given parent, if not NULL).
 * This function initializes the data structures and creates the appropriate
 * X11 IDs using x_con_init().
 *
 */
Con *con_new(Con *parent, i3Window *window) {
    Con *new = scalloc(sizeof(Con));
    new->on_remove_child = con_on_remove_child;
    TAILQ_INSERT_TAIL(&all_cons, new, all_cons);
    new->type = CT_CON;
    new->window = window;
    new->border_style = config.default_border;
    new->current_border_width = -1;
    static int cnt = 0;
    DLOG("opening window %d\n", cnt);

    /* TODO: remove window coloring after test-phase */
    DLOG("color %s\n", colors[cnt]);
    new->name = strdup(colors[cnt]);
    //uint32_t cp = get_colorpixel(colors[cnt]);
    cnt++;
    if ((cnt % (sizeof(colors) / sizeof(char*))) == 0)
        cnt = 0;
    if (window)
        x_con_init(new, window->depth);
    else
        x_con_init(new, XCB_COPY_FROM_PARENT);

    TAILQ_INIT(&(new->floating_head));
    TAILQ_INIT(&(new->nodes_head));
    TAILQ_INIT(&(new->focus_head));
    TAILQ_INIT(&(new->swallow_head));

    if (parent != NULL)
        con_attach(new, parent, false);

    return new;
}

/*
 * Attaches the given container to the given parent. This happens when moving
 * a container or when inserting a new container at a specific place in the
 * tree.
 *
 * ignore_focus is to just insert the Con at the end (useful when creating a
 * new split container *around* some containers, that is, detaching and
 * attaching them in order without wanting to mess with the focus in between).
 *
 */
void con_attach(Con *con, Con *parent, bool ignore_focus) {
    con->parent = parent;
    Con *loop;
    Con *current = NULL;
    struct nodes_head *nodes_head = &(parent->nodes_head);
    struct focus_head *focus_head = &(parent->focus_head);

    /* Workspaces are handled differently: they need to be inserted at the
     * right position. */
    if (con->type == CT_WORKSPACE) {
        DLOG("it's a workspace. num = %d\n", con->num);
        if (con->num == -1 || TAILQ_EMPTY(nodes_head)) {
            TAILQ_INSERT_TAIL(nodes_head, con, nodes);
        } else {
            current = TAILQ_FIRST(nodes_head);
            if (con->num < current->num) {
                /* we need to insert the container at the beginning */
                TAILQ_INSERT_HEAD(nodes_head, con, nodes);
            } else {
                while (current->num != -1 && con->num > current->num) {
                    current = TAILQ_NEXT(current, nodes);
                    if (current == TAILQ_END(nodes_head)) {
                        current = NULL;
                        break;
                    }
                }
                /* we need to insert con after current, if current is not NULL */
                if (current)
                    TAILQ_INSERT_BEFORE(current, con, nodes);
                else TAILQ_INSERT_TAIL(nodes_head, con, nodes);
            }
        }
        goto add_to_focus_head;
    }

    if (con->type == CT_FLOATING_CON) {
        DLOG("Inserting into floating containers\n");
        TAILQ_INSERT_TAIL(&(parent->floating_head), con, floating_windows);
    } else {
        if (!ignore_focus) {
            /* Get the first tiling container in focus stack */
            TAILQ_FOREACH(loop, &(parent->focus_head), focused) {
                if (loop->type == CT_FLOATING_CON)
                    continue;
                current = loop;
                break;
            }
        }

        /* When the container is not a split container (but contains a window)
         * and is attached to a workspace, we check if the user configured a
         * workspace_layout. This is done in workspace_attach_to, which will
         * provide us with the container to which we should attach (either the
         * workspace or a new split container with the configured
         * workspace_layout).
         */
        if (con->window != NULL &&
            parent->type == CT_WORKSPACE &&
            parent->workspace_layout != L_DEFAULT) {
            DLOG("Parent is a workspace. Applying default layout...\n");
            Con *target = workspace_attach_to(parent);

            /* Attach the original con to this new split con instead */
            nodes_head = &(target->nodes_head);
            focus_head = &(target->focus_head);
            con->parent = target;
            current = NULL;

            DLOG("done\n");
        }

        /* Insert the container after the tiling container, if found.
         * When adding to a CT_OUTPUT, just append one after another. */
        if (current && parent->type != CT_OUTPUT) {
            DLOG("Inserting con = %p after last focused tiling con %p\n",
                 con, current);
            TAILQ_INSERT_AFTER(nodes_head, current, con, nodes);
        } else TAILQ_INSERT_TAIL(nodes_head, con, nodes);
    }

add_to_focus_head:
    /* We insert to the TAIL because con_focus() will correct this.
     * This way, we have the option to insert Cons without having
     * to focus them. */
    TAILQ_INSERT_TAIL(focus_head, con, focused);
    con_force_split_parents_redraw(con);
}

/*
 * Detaches the given container from its current parent
 *
 */
void con_detach(Con *con) {
    con_force_split_parents_redraw(con);
    if (con->type == CT_FLOATING_CON) {
        TAILQ_REMOVE(&(con->parent->floating_head), con, floating_windows);
        TAILQ_REMOVE(&(con->parent->focus_head), con, focused);
    } else {
        TAILQ_REMOVE(&(con->parent->nodes_head), con, nodes);
        TAILQ_REMOVE(&(con->parent->focus_head), con, focused);
    }
}

/*
 * Sets input focus to the given container. Will be updated in X11 in the next
 * run of x_push_changes().
 *
 */
void con_focus(Con *con) {
    assert(con != NULL);
    DLOG("con_focus = %p\n", con);

    /* 1: set focused-pointer to the new con */
    /* 2: exchange the position of the container in focus stack of the parent all the way up */
    TAILQ_REMOVE(&(con->parent->focus_head), con, focused);
    TAILQ_INSERT_HEAD(&(con->parent->focus_head), con, focused);
    if (con->parent->parent != NULL)
        con_focus(con->parent);

    focused = con;
    /* We can't blindly reset non-leaf containers since they might have
     * other urgent children. Therefore we only reset leafs and propagate
     * the changes upwards via con_update_parents_urgency() which does proper
     * checks before resetting the urgency.
     */
    if (con->urgent && con_is_leaf(con)) {
        con->urgent = false;
        con_update_parents_urgency(con);
        workspace_update_urgent_flag(con_get_workspace(con));
    }
}

/*
 * Returns true when this node is a leaf node (has no children)
 *
 */
bool con_is_leaf(Con *con) {
    return TAILQ_EMPTY(&(con->nodes_head));
}

/**
 * Returns true if this node has regular or floating children.
 *
 */
bool con_has_children(Con *con) {
    return (!con_is_leaf(con) || !TAILQ_EMPTY(&(con->floating_head)));
}

/*
 * Returns true if a container should be considered split.
 *
 */
bool con_is_split(Con *con) {
    if (con_is_leaf(con))
        return false;

    switch (con->layout) {
        case L_DOCKAREA:
        case L_OUTPUT:
            return false;

        default:
            return true;
    }
}

/*
 * Returns true if this node accepts a window (if the node swallows windows,
 * it might already have swallowed enough and cannot hold any more).
 *
 */
bool con_accepts_window(Con *con) {
    /* 1: workspaces never accept direct windows */
    if (con->type == CT_WORKSPACE)
        return false;

    if (con_is_split(con)) {
        DLOG("container %p does not accept windows, it is a split container.\n", con);
        return false;
    }

    /* TODO: if this is a swallowing container, we need to check its max_clients */
    return (con->window == NULL);
}

/*
 * Gets the output container (first container with CT_OUTPUT in hierarchy) this
 * node is on.
 *
 */
Con *con_get_output(Con *con) {
    Con *result = con;
    while (result != NULL && result->type != CT_OUTPUT)
        result = result->parent;
    /* We must be able to get an output because focus can never be set higher
     * in the tree (root node cannot be focused). */
    assert(result != NULL);
    return result;
}

/*
 * Gets the workspace container this node is on.
 *
 */
Con *con_get_workspace(Con *con) {
    Con *result = con;
    while (result != NULL && result->type != CT_WORKSPACE)
        result = result->parent;
    return result;
}

/*
 * Searches parenst of the given 'con' until it reaches one with the specified
 * 'orientation'. Aborts when it comes across a floating_con.
 *
 */
Con *con_parent_with_orientation(Con *con, orientation_t orientation) {
    DLOG("Searching for parent of Con %p with orientation %d\n", con, orientation);
    Con *parent = con->parent;
    if (parent->type == CT_FLOATING_CON)
        return NULL;
    while (con_orientation(parent) != orientation) {
        DLOG("Need to go one level further up\n");
        parent = parent->parent;
        /* Abort when we reach a floating con, or an output con */
        if (parent &&
            (parent->type == CT_FLOATING_CON ||
             parent->type == CT_OUTPUT ||
             (parent->parent && parent->parent->type == CT_OUTPUT)))
            parent = NULL;
        if (parent == NULL)
            break;
    }
    DLOG("Result: %p\n", parent);
    return parent;
}

/*
 * helper data structure for the breadth-first-search in
 * con_get_fullscreen_con()
 *
 */
struct bfs_entry {
    Con *con;

    TAILQ_ENTRY(bfs_entry) entries;
};

/*
 * Returns the first fullscreen node below this node.
 *
 */
Con *con_get_fullscreen_con(Con *con, int fullscreen_mode) {
    Con *current, *child;

    /* TODO: is breadth-first-search really appropriate? (check as soon as
     * fullscreen levels and fullscreen for containers is implemented) */
    TAILQ_HEAD(bfs_head, bfs_entry) bfs_head = TAILQ_HEAD_INITIALIZER(bfs_head);
    struct bfs_entry *entry = smalloc(sizeof(struct bfs_entry));
    entry->con = con;
    TAILQ_INSERT_TAIL(&bfs_head, entry, entries);

    while (!TAILQ_EMPTY(&bfs_head)) {
        entry = TAILQ_FIRST(&bfs_head);
        current = entry->con;
        if (current != con && current->fullscreen_mode == fullscreen_mode) {
            /* empty the queue */
            while (!TAILQ_EMPTY(&bfs_head)) {
                entry = TAILQ_FIRST(&bfs_head);
                TAILQ_REMOVE(&bfs_head, entry, entries);
                free(entry);
            }
            return current;
        }

        TAILQ_REMOVE(&bfs_head, entry, entries);
        free(entry);

        TAILQ_FOREACH(child, &(current->nodes_head), nodes) {
            entry = smalloc(sizeof(struct bfs_entry));
            entry->con = child;
            TAILQ_INSERT_TAIL(&bfs_head, entry, entries);
        }

        TAILQ_FOREACH(child, &(current->floating_head), floating_windows) {
            entry = smalloc(sizeof(struct bfs_entry));
            entry->con = child;
            TAILQ_INSERT_TAIL(&bfs_head, entry, entries);
        }
    }

    return NULL;
}

/**
 * Returns true if the container is internal, such as __i3_scratch
 *
 */
bool con_is_internal(Con *con) {
    return (con->name[0] == '_' && con->name[1] == '_');
}

/*
 * Returns true if the node is floating.
 *
 */
bool con_is_floating(Con *con) {
    assert(con != NULL);
    DLOG("checking if con %p is floating\n", con);
    return (con->floating >= FLOATING_AUTO_ON);
}

/*
 * Checks if the given container is either floating or inside some floating
 * container. It returns the FLOATING_CON container.
 *
 */
Con *con_inside_floating(Con *con) {
    assert(con != NULL);
    if (con->type == CT_FLOATING_CON)
        return con;

    if (con->floating >= FLOATING_AUTO_ON)
        return con->parent;

    if (con->type == CT_WORKSPACE || con->type == CT_OUTPUT)
        return NULL;

    return con_inside_floating(con->parent);
}

/*
 * Checks if the given container is inside a focused container.
 *
 */
bool con_inside_focused(Con *con) {
    if (con == focused)
        return true;
    if (!con->parent)
        return false;
    return con_inside_focused(con->parent);
}

/*
 * Returns the container with the given client window ID or NULL if no such
 * container exists.
 *
 */
Con *con_by_window_id(xcb_window_t window) {
    Con *con;
    TAILQ_FOREACH(con, &all_cons, all_cons)
        if (con->window != NULL && con->window->id == window)
            return con;
    return NULL;
}

/*
 * Returns the container with the given frame ID or NULL if no such container
 * exists.
 *
 */
Con *con_by_frame_id(xcb_window_t frame) {
    Con *con;
    TAILQ_FOREACH(con, &all_cons, all_cons)
        if (con->frame == frame)
            return con;
    return NULL;
}

/*
 * Returns the first container below 'con' which wants to swallow this window
 * TODO: priority
 *
 */
Con *con_for_window(Con *con, i3Window *window, Match **store_match) {
    Con *child;
    Match *match;
    //DLOG("searching con for window %p starting at con %p\n", window, con);
    //DLOG("class == %s\n", window->class_class);

    TAILQ_FOREACH(child, &(con->nodes_head), nodes) {
        TAILQ_FOREACH(match, &(child->swallow_head), matches) {
            if (!match_matches_window(match, window))
                continue;
            if (store_match != NULL)
                *store_match = match;
            return child;
        }
        Con *result = con_for_window(child, window, store_match);
        if (result != NULL)
            return result;
    }

    TAILQ_FOREACH(child, &(con->floating_head), floating_windows) {
        TAILQ_FOREACH(match, &(child->swallow_head), matches) {
            if (!match_matches_window(match, window))
                continue;
            if (store_match != NULL)
                *store_match = match;
            return child;
        }
        Con *result = con_for_window(child, window, store_match);
        if (result != NULL)
            return result;
    }

    return NULL;
}

/*
 * Returns the number of children of this container.
 *
 */
int con_num_children(Con *con) {
    Con *child;
    int children = 0;

    TAILQ_FOREACH(child, &(con->nodes_head), nodes)
        children++;

    return children;
}

/*
 * Updates the percent attribute of the children of the given container. This
 * function needs to be called when a window is added or removed from a
 * container.
 *
 */
void con_fix_percent(Con *con) {
    Con *child;
    int children = con_num_children(con);

    // calculate how much we have distributed and how many containers
    // with a percentage set we have
    double total = 0.0;
    int children_with_percent = 0;
    TAILQ_FOREACH(child, &(con->nodes_head), nodes) {
        if (child->percent > 0.0) {
            total += child->percent;
            ++children_with_percent;
        }
    }

    // if there were children without a percentage set, set to a value that
    // will make those children proportional to all others
    if (children_with_percent != children) {
        TAILQ_FOREACH(child, &(con->nodes_head), nodes) {
            if (child->percent <= 0.0) {
                if (children_with_percent == 0)
                    total += (child->percent = 1.0);
                else total += (child->percent = total / children_with_percent);
            }
        }
    }

    // if we got a zero, just distribute the space equally, otherwise
    // distribute according to the proportions we got
    if (total == 0.0) {
        TAILQ_FOREACH(child, &(con->nodes_head), nodes)
            child->percent = 1.0 / children;
    } else if (total != 1.0) {
        TAILQ_FOREACH(child, &(con->nodes_head), nodes)
            child->percent /= total;
    }
}

/*
 * Toggles fullscreen mode for the given container. Fullscreen mode will not be
 * entered when there already is a fullscreen container on this workspace.
 *
 */
void con_toggle_fullscreen(Con *con, int fullscreen_mode) {
    Con *workspace, *fullscreen;

    if (con->type == CT_WORKSPACE) {
        DLOG("You cannot make a workspace fullscreen.\n");
        return;
    }

    DLOG("toggling fullscreen for %p / %s\n", con, con->name);
    if (con->fullscreen_mode == CF_NONE) {
        /* 1: check if there already is a fullscreen con */
        if (fullscreen_mode == CF_GLOBAL)
            fullscreen = con_get_fullscreen_con(croot, CF_GLOBAL);
        else {
            workspace = con_get_workspace(con);
            fullscreen = con_get_fullscreen_con(workspace, CF_OUTPUT);
        }
        if (fullscreen != NULL) {
            /* Disable fullscreen for the currently fullscreened
             * container and enable it for the one the user wants
             * to have in fullscreen mode. */
            LOG("Disabling fullscreen for (%p/%s) upon user request\n",
                fullscreen, fullscreen->name);
            fullscreen->fullscreen_mode = CF_NONE;
        }

        /* 2: enable fullscreen */
        con->fullscreen_mode = fullscreen_mode;
    } else {
        /* 1: disable fullscreen */
        con->fullscreen_mode = CF_NONE;
    }

    DLOG("mode now: %d\n", con->fullscreen_mode);

    /* update _NET_WM_STATE if this container has a window */
    /* TODO: when a window is assigned to a container which is already
     * fullscreened, this state needs to be pushed to the client, too */
    if (con->window == NULL)
        return;

    uint32_t values[1];
    unsigned int num = 0;

    if (con->fullscreen_mode != CF_NONE)
        values[num++] = A__NET_WM_STATE_FULLSCREEN;

    xcb_change_property(conn, XCB_PROP_MODE_REPLACE, con->window->id,
                        A__NET_WM_STATE, XCB_ATOM_ATOM, 32, num, values);
}

/*
 * Moves the given container to the currently focused container on the given
 * workspace.
 *
 * The fix_coordinates flag will translate the current coordinates (offset from
 * the monitor position basically) to appropriate coordinates on the
 * destination workspace.
 * Not enabling this behaviour comes in handy when this function gets called by
 * floating_maybe_reassign_ws, which will only "move" a floating window when it
 * *already* changed its coordinates to a different output.
 *
 * The dont_warp flag disables pointer warping and will be set when this
 * function is called while dragging a floating window.
 *
 * TODO: is there a better place for this function?
 *
 */
void con_move_to_workspace(Con *con, Con *workspace, bool fix_coordinates, bool dont_warp) {
    /* Prevent moving if this would violate the fullscreen focus restrictions. */
    if (!con_fullscreen_permits_focusing(workspace)) {
        LOG("Cannot move out of a fullscreen container");
        return;
    }

    if (con_is_floating(con)) {
        DLOG("Using FLOATINGCON instead\n");
        con = con->parent;
    }

    Con *source_ws = con_get_workspace(con);
    if (workspace == source_ws) {
        DLOG("Not moving, already there\n");
        return;
    }

    if (con->type == CT_WORKSPACE) {
        /* Re-parent all of the old workspace's floating windows. */
        Con *child;
        while (!TAILQ_EMPTY(&(source_ws->floating_head))) {
            child = TAILQ_FIRST(&(source_ws->floating_head));
            con_move_to_workspace(child, workspace, true, true);
        }

        /* If there are no non-floating children, ignore the workspace. */
        if (con_is_leaf(con))
            return;

        con = workspace_encapsulate(con);
        if (con == NULL) {
            ELOG("Workspace failed to move its contents into a container!\n");
            return;
        }
    }

    /* Save the current workspace. So we can call workspace_show() by the end
     * of this function. */
    Con *current_ws = con_get_workspace(focused);

    Con *source_output = con_get_output(con),
        *dest_output = con_get_output(workspace);

    /* 1: save the container which is going to be focused after the current
     * container is moved away */
    Con *focus_next = con_next_focused(con);

    /* 2: get the focused container of this workspace */
    Con *next = con_descend_focused(workspace);

    /* 3: we go up one level, but only when next is a normal container */
    if (next->type != CT_WORKSPACE) {
        DLOG("next originally = %p / %s / type %d\n", next, next->name, next->type);
        next = next->parent;
    }

    /* 4: if the target container is floating, we get the workspace instead.
     * Only tiling windows need to get inserted next to the current container.
     * */
    Con *floatingcon = con_inside_floating(next);
    if (floatingcon != NULL) {
        DLOG("floatingcon, going up even further\n");
        next = floatingcon->parent;
    }

    if (con->type == CT_FLOATING_CON) {
        Con *ws = con_get_workspace(next);
        DLOG("This is a floating window, using workspace %p / %s\n", ws, ws->name);
        next = ws;
    }

    if (source_output != dest_output) {
        /* Take the relative coordinates of the current output, then add them
         * to the coordinate space of the correct output */
        if (fix_coordinates && con->type == CT_FLOATING_CON) {
            floating_fix_coordinates(con, &(source_output->rect), &(dest_output->rect));
        } else DLOG("Not fixing coordinates, fix_coordinates flag = %d\n", fix_coordinates);

        /* If moving to a visible workspace, call show so it can be considered
         * focused. Must do before attaching because workspace_show checks to see
         * if focused container is in its area. */
        if (workspace_is_visible(workspace)) {
            workspace_show(workspace);

            /* Don’t warp if told so (when dragging floating windows with the
             * mouse for example) */
            if (dont_warp)
                x_set_warp_to(NULL);
            else
                x_set_warp_to(&(con->rect));
        }
    }

    /* If moving a fullscreen container and the destination already has a
     * fullscreen window on it, un-fullscreen the target's fullscreen con. */
    Con *fullscreen = con_get_fullscreen_con(workspace, CF_OUTPUT);
    if (con->fullscreen_mode != CF_NONE && fullscreen != NULL) {
        con_toggle_fullscreen(fullscreen, CF_OUTPUT);
        fullscreen = NULL;
    }

    DLOG("Re-attaching container to %p / %s\n", next, next->name);
    /* 5: re-attach the con to the parent of this focused container */
    Con *parent = con->parent;
    con_detach(con);
    con_attach(con, next, false);

    /* 6: fix the percentages */
    con_fix_percent(parent);
    con->percent = 0.0;
    con_fix_percent(next);

    /* 7: focus the con on the target workspace, but only within that
     * workspace, that is, don’t move focus away if the target workspace is
     * invisible.
     * We don’t focus the con for i3 pseudo workspaces like __i3_scratch and
     * we don’t focus when there is a fullscreen con on that workspace. */
    if (!con_is_internal(workspace) && !fullscreen) {
        /* We need to save the focused workspace on the output in case the
         * new workspace is hidden and it's necessary to immediately switch
         * back to the originally-focused workspace. */
        Con *old_focus = TAILQ_FIRST(&(output_get_content(dest_output)->focus_head));
        con_focus(con_descend_focused(con));

        /* Restore focus if the output's focused workspace has changed. */
        if (con_get_workspace(focused) != old_focus)
            con_focus(old_focus);
    }

    /* 8: when moving to a visible workspace on a different output, we keep the
     * con focused. Otherwise, we leave the focus on the current workspace as we
     * don’t want to focus invisible workspaces */
    if (source_output != dest_output &&
        workspace_is_visible(workspace) &&
        !con_is_internal(workspace)) {
        DLOG("Moved to a different output, focusing target\n");
    } else {
        /* Descend focus stack in case focus_next is a workspace which can
         * occur if we move to the same workspace.  Also show current workspace
         * to ensure it is focused. */
        workspace_show(current_ws);

        /* Set focus only if con was on current workspace before moving.
         * Otherwise we would give focus to some window on different workspace. */
        if (source_ws == current_ws)
            con_focus(con_descend_focused(focus_next));
    }

    /* If anything within the container is associated with a startup sequence,
     * delete it so child windows won't be created on the old workspace. */
    struct Startup_Sequence *sequence;
    xcb_get_property_cookie_t cookie;
    xcb_get_property_reply_t *startup_id_reply;

    if (!con_is_leaf(con)) {
        Con *child;
        TAILQ_FOREACH(child, &(con->nodes_head), nodes) {
            if (!child->window)
                continue;

            cookie = xcb_get_property(conn, false, child->window->id,
                A__NET_STARTUP_ID, XCB_GET_PROPERTY_TYPE_ANY, 0, 512);
            startup_id_reply = xcb_get_property_reply(conn, cookie, NULL);

            sequence = startup_sequence_get(child->window, startup_id_reply, true);
            if (sequence != NULL)
                startup_sequence_delete(sequence);
        }
    }

    if (con->window) {
        cookie = xcb_get_property(conn, false, con->window->id,
            A__NET_STARTUP_ID, XCB_GET_PROPERTY_TYPE_ANY, 0, 512);
        startup_id_reply = xcb_get_property_reply(conn, cookie, NULL);

        sequence = startup_sequence_get(con->window, startup_id_reply, true);
        if (sequence != NULL)
            startup_sequence_delete(sequence);
    }

    CALL(parent, on_remove_child);
}

/*
 * Returns the orientation of the given container (for stacked containers,
 * vertical orientation is used regardless of the actual orientation of the
 * container).
 *
 */
int con_orientation(Con *con) {
    switch (con->layout) {
        case L_SPLITV:
        /* stacking containers behave like they are in vertical orientation */
        case L_STACKED:
            return VERT;

        case L_SPLITH:
        /* tabbed containers behave like they are in vertical orientation */
        case L_TABBED:
            return HORIZ;

        case L_DEFAULT:
            DLOG("Someone called con_orientation() on a con with L_DEFAULT, this is a bug in the code.\n");
            assert(false);
            return HORIZ;

        case L_DOCKAREA:
        case L_OUTPUT:
            DLOG("con_orientation() called on dockarea/output (%d) container %p\n", con->layout, con);
            assert(false);
            return HORIZ;

        default:
            DLOG("con_orientation() ran into default\n");
            assert(false);
    }
}

/*
 * Returns the container which will be focused next when the given container
 * is not available anymore. Called in tree_close and con_move_to_workspace
 * to properly restore focus.
 *
 */
Con *con_next_focused(Con *con) {
    Con *next;
    /* floating containers are attached to a workspace, so we focus either the
     * next floating container (if any) or the workspace itself. */
    if (con->type == CT_FLOATING_CON) {
        DLOG("selecting next for CT_FLOATING_CON\n");
        next = TAILQ_NEXT(con, floating_windows);
        DLOG("next = %p\n", next);
        if (!next) {
            next = TAILQ_PREV(con, floating_head, floating_windows);
            DLOG("using prev, next = %p\n", next);
        }
        if (!next) {
            Con *ws = con_get_workspace(con);
            next = ws;
            DLOG("no more floating containers for next = %p, restoring workspace focus\n", next);
            while (next != TAILQ_END(&(ws->focus_head)) && !TAILQ_EMPTY(&(next->focus_head))) {
                next = TAILQ_FIRST(&(next->focus_head));
                if (next == con) {
                    DLOG("skipping container itself, we want the next client\n");
                    next = TAILQ_NEXT(next, focused);
                }
            }
            if (next == TAILQ_END(&(ws->focus_head))) {
                DLOG("Focus list empty, returning ws\n");
                next = ws;
            }
        } else {
            /* Instead of returning the next CT_FLOATING_CON, we descend it to
             * get an actual window to focus. */
            next = con_descend_focused(next);
        }
        return next;
    }

    /* dock clients cannot be focused, so we focus the workspace instead */
    if (con->parent->type == CT_DOCKAREA) {
        DLOG("selecting workspace for dock client\n");
        return con_descend_focused(output_get_content(con->parent->parent));
    }

    /* if 'con' is not the first entry in the focus stack, use the first one as
     * it’s currently focused already */
    Con *first = TAILQ_FIRST(&(con->parent->focus_head));
    if (first != con) {
        DLOG("Using first entry %p\n", first);
        next = first;
    } else {
        /* try to focus the next container on the same level as this one or fall
         * back to its parent */
        if (!(next = TAILQ_NEXT(con, focused)))
            next = con->parent;
    }

    /* now go down the focus stack as far as
     * possible, excluding the current container */
    while (!TAILQ_EMPTY(&(next->focus_head)) &&
           TAILQ_FIRST(&(next->focus_head)) != con)
        next = TAILQ_FIRST(&(next->focus_head));

    return next;
}

/*
 * Get the next/previous container in the specified orientation. This may
 * travel up until it finds a container with suitable orientation.
 *
 */
Con *con_get_next(Con *con, char way, orientation_t orientation) {
    DLOG("con_get_next(way=%c, orientation=%d)\n", way, orientation);
    /* 1: get the first parent with the same orientation */
    Con *cur = con;
    while (con_orientation(cur->parent) != orientation) {
        DLOG("need to go one level further up\n");
        if (cur->parent->type == CT_WORKSPACE) {
            LOG("that's a workspace, we can't go further up\n");
            return NULL;
        }
        cur = cur->parent;
    }

    /* 2: chose next (or previous) */
    Con *next;
    if (way == 'n') {
        next = TAILQ_NEXT(cur, nodes);
        /* if we are at the end of the list, we need to wrap */
        if (next == TAILQ_END(&(parent->nodes_head)))
            return NULL;
    } else {
        next = TAILQ_PREV(cur, nodes_head, nodes);
        /* if we are at the end of the list, we need to wrap */
        if (next == TAILQ_END(&(cur->nodes_head)))
            return NULL;
    }
    DLOG("next = %p\n", next);

    return next;
}

/*
 * Returns the focused con inside this client, descending the tree as far as
 * possible. This comes in handy when attaching a con to a workspace at the
 * currently focused position, for example.
 *
 */
Con *con_descend_focused(Con *con) {
    Con *next = con;
    while (next != focused && !TAILQ_EMPTY(&(next->focus_head)))
        next = TAILQ_FIRST(&(next->focus_head));
    return next;
}

/*
 * Returns the focused con inside this client, descending the tree as far as
 * possible. This comes in handy when attaching a con to a workspace at the
 * currently focused position, for example.
 *
 * Works like con_descend_focused but considers only tiling cons.
 *
 */
Con *con_descend_tiling_focused(Con *con) {
    Con *next = con;
    Con *before;
    Con *child;
    if (next == focused)
        return next;
    do {
        before = next;
        TAILQ_FOREACH(child, &(next->focus_head), focused) {
            if (child->type == CT_FLOATING_CON)
                continue;

            next = child;
            break;
        }
    } while (before != next && next != focused);
    return next;
}

/*
 * Returns the leftmost, rightmost, etc. container in sub-tree. For example, if
 * direction is D_LEFT, then we return the rightmost container and if direction
 * is D_RIGHT, we return the leftmost container.  This is because if we are
 * moving D_LEFT, and thus want the rightmost container.
 *
 */
Con *con_descend_direction(Con *con, direction_t direction) {
    Con *most = NULL;
    Con *current;
    int orientation = con_orientation(con);
    DLOG("con_descend_direction(%p, orientation %d, direction %d)\n", con, orientation, direction);
    if (direction == D_LEFT || direction == D_RIGHT) {
        if (orientation == HORIZ) {
            /* If the direction is horizontal, we can use either the first
             * (D_RIGHT) or the last con (D_LEFT) */
            if (direction == D_RIGHT)
                most = TAILQ_FIRST(&(con->nodes_head));
            else most = TAILQ_LAST(&(con->nodes_head), nodes_head);
        } else if (orientation == VERT) {
            /* Wrong orientation. We use the last focused con. Within that con,
             * we recurse to chose the left/right con or at least the last
             * focused one. */
            TAILQ_FOREACH(current, &(con->focus_head), focused) {
                if (current->type != CT_FLOATING_CON) {
                    most = current;
                    break;
                }
            }
        } else {
            /* If the con has no orientation set, it’s not a split container
             * but a container with a client window, so stop recursing */
            return con;
        }
    }

    if (direction == D_UP || direction == D_DOWN) {
        if (orientation == VERT) {
            /* If the direction is vertical, we can use either the first
             * (D_DOWN) or the last con (D_UP) */
            if (direction == D_UP)
                most = TAILQ_LAST(&(con->nodes_head), nodes_head);
            else most = TAILQ_FIRST(&(con->nodes_head));
        } else if (orientation == HORIZ) {
            /* Wrong orientation. We use the last focused con. Within that con,
             * we recurse to chose the top/bottom con or at least the last
             * focused one. */
            TAILQ_FOREACH(current, &(con->focus_head), focused) {
                if (current->type != CT_FLOATING_CON) {
                    most = current;
                    break;
                }
            }
        } else {
            /* If the con has no orientation set, it’s not a split container
             * but a container with a client window, so stop recursing */
            return con;
        }
    }

    if (!most)
        return con;
    return con_descend_direction(most, direction);
}

/*
 * Returns a "relative" Rect which contains the amount of pixels that need to
 * be added to the original Rect to get the final position (obviously the
 * amount of pixels for normal, 1pixel and borderless are different).
 *
 */
Rect con_border_style_rect(Con *con) {
    adjacent_t borders_to_hide = ADJ_NONE;
    int border_width = con->current_border_width;
    DLOG("The border width for con is set to: %d\n", con->current_border_width);
    Rect result;
    if (con->current_border_width < 0)
        border_width = config.default_border_width;
    DLOG("Effective border width is set to: %d\n", border_width);
    /* Shortcut to avoid calling con_adjacent_borders() on dock containers. */
    int border_style = con_border_style(con);
    if (border_style == BS_NONE)
        return (Rect){ 0, 0, 0, 0 };
    borders_to_hide = con_adjacent_borders(con) & config.hide_edge_borders;
    if (border_style == BS_NORMAL) {
        result = (Rect){border_width, 0 , -(2 * border_width), -(border_width)};
    } else {
        result = (Rect){border_width, border_width, -(2 * border_width), -(2 * border_width)};
    }
    if (borders_to_hide & ADJ_LEFT_SCREEN_EDGE) {
        result.x -= border_width;
        result.width += border_width;
    }
    if (borders_to_hide & ADJ_RIGHT_SCREEN_EDGE) {
        result.width += border_width;
    }
    if (borders_to_hide & ADJ_UPPER_SCREEN_EDGE && (border_style != BS_NORMAL)) {
        result.y -= border_width;
        result.height += border_width;
    }
    if (borders_to_hide & ADJ_LOWER_SCREEN_EDGE) {
        result.height += border_width;
    }
    return result;

}

/*
 * Returns adjacent borders of the window. We need this if hide_edge_borders is
 * enabled.
 */
adjacent_t con_adjacent_borders(Con *con) {
    adjacent_t result = ADJ_NONE;
    Con *workspace = con_get_workspace(con);
    if (con->rect.x == workspace->rect.x)
        result |= ADJ_LEFT_SCREEN_EDGE;
    if (con->rect.x + con->rect.width == workspace->rect.x + workspace->rect.width)
        result |= ADJ_RIGHT_SCREEN_EDGE;
    if (con->rect.y == workspace->rect.y)
        result |= ADJ_UPPER_SCREEN_EDGE;
    if (con->rect.y + con->rect.height == workspace->rect.y + workspace->rect.height)
        result |= ADJ_LOWER_SCREEN_EDGE;
    return result;
}

/*
 * Use this function to get a container’s border style. This is important
 * because when inside a stack, the border style is always BS_NORMAL.
 * For tabbed mode, the same applies, with one exception: when the container is
 * borderless and the only element in the tabbed container, the border is not
 * rendered.
 *
 * For children of a CT_DOCKAREA, the border style is always none.
 *
 */
int con_border_style(Con *con) {
    Con *fs = con_get_fullscreen_con(con->parent, CF_OUTPUT);
    if (fs == con) {
        DLOG("this one is fullscreen! overriding BS_NONE\n");
        return BS_NONE;
    }

    if (con->parent->layout == L_STACKED)
        return (con_num_children(con->parent) == 1 ? con->border_style : BS_NORMAL);

    if (con->parent->layout == L_TABBED && con->border_style != BS_NORMAL)
        return (con_num_children(con->parent) == 1 ? con->border_style : BS_NORMAL);

    if (con->parent->type == CT_DOCKAREA)
        return BS_NONE;

    return con->border_style;
}

/*
 * Sets the given border style on con, correctly keeping the position/size of a
 * floating window.
 *
 */
void con_set_border_style(Con *con, int border_style, int border_width) {
    /* Handle the simple case: non-floating containerns */
    if (!con_is_floating(con)) {
        con->border_style = border_style;
        con->current_border_width = border_width;
        return;
    }

    /* For floating containers, we want to keep the position/size of the
     * *window* itself. We first add the border pixels to con->rect to make
     * con->rect represent the absolute position of the window. Then, we change
     * the border and subtract the new border pixels. Afterwards, we update
     * parent->rect to contain con. */
    DLOG("This is a floating container\n");

    Rect bsr = con_border_style_rect(con);
    con->rect.x += bsr.x;
    con->rect.y += bsr.y;
    con->rect.width += bsr.width;
    con->rect.height += bsr.height;

    /* Change the border style, get new border/decoration values. */
    con->border_style = border_style;
    con->current_border_width = border_width;
    bsr = con_border_style_rect(con);
    int deco_height =
        (con->border_style == BS_NORMAL ? config.font.height + 5 : 0);

    con->rect.x -= bsr.x;
    con->rect.y -= bsr.y;
    con->rect.width -= bsr.width;
    con->rect.height -= bsr.height;

    Con *parent = con->parent;
    parent->rect.x = con->rect.x;
    parent->rect.y = con->rect.y - deco_height;
    parent->rect.width = con->rect.width;
    parent->rect.height = con->rect.height + deco_height;
}

/*
 * This function changes the layout of a given container. Use it to handle
 * special cases like changing a whole workspace to stacked/tabbed (creates a
 * new split container before).
 *
 */
void con_set_layout(Con *con, int layout) {
    DLOG("con_set_layout(%p, %d), con->type = %d\n",
         con, layout, con->type);

    /* Users can focus workspaces, but not any higher in the hierarchy.
     * Focus on the workspace is a special case, since in every other case, the
     * user means "change the layout of the parent split container". */
    if (con->type != CT_WORKSPACE)
        con = con->parent;

    /* We fill in last_split_layout when switching to a different layout
     * since there are many places in the code that don’t use
     * con_set_layout(). */
    if (con->layout == L_SPLITH || con->layout == L_SPLITV)
        con->last_split_layout = con->layout;

    /* When the container type is CT_WORKSPACE, the user wants to change the
     * whole workspace into stacked/tabbed mode. To do this and still allow
     * intuitive operations (like level-up and then opening a new window), we
     * need to create a new split container. */
    if (con->type == CT_WORKSPACE &&
        (layout == L_STACKED || layout == L_TABBED)) {
        if (con_num_children(con) == 0) {
            DLOG("Setting workspace_layout to %d\n", layout);
            con->workspace_layout = layout;
        } else {
            DLOG("Creating new split container\n");
            /* 1: create a new split container */
            Con *new = con_new(NULL, NULL);
            new->parent = con;

            /* 2: Set the requested layout on the split container and mark it as
             * split. */
            new->layout = layout;
            new->last_split_layout = con->last_split_layout;

            Con *old_focused = TAILQ_FIRST(&(con->focus_head));
            if (old_focused == TAILQ_END(&(con->focus_head)))
                old_focused = NULL;

            /* 3: move the existing cons of this workspace below the new con */
            DLOG("Moving cons\n");
            Con *child;
            while (!TAILQ_EMPTY(&(con->nodes_head))) {
                child = TAILQ_FIRST(&(con->nodes_head));
                con_detach(child);
                con_attach(child, new, true);
            }

            /* 4: attach the new split container to the workspace */
            DLOG("Attaching new split to ws\n");
            con_attach(new, con, false);

            if (old_focused)
                con_focus(old_focused);

            tree_flatten(croot);
        }
        con_force_split_parents_redraw(con);
        return;
    }

    if (layout == L_DEFAULT) {
        /* Special case: the layout formerly known as "default" (in combination
         * with an orientation). Since we switched to splith/splitv layouts,
         * using the "default" layout (which "only" should happen when using
         * legacy configs) is using the last split layout (either splith or
         * splitv) in order to still do the same thing.
         *
         * Starting from v4.6 though, we will nag users about using "layout
         * default", and in v4.9 we will remove it entirely (with an
         * appropriate i3-migrate-config mechanism). */
        con->layout = con->last_split_layout;
        /* In case last_split_layout was not initialized… */
        if (con->layout == L_DEFAULT)
            con->layout = L_SPLITH;
    } else {
        con->layout = layout;
    }
    con_force_split_parents_redraw(con);
}

/*
 * This function toggles the layout of a given container. toggle_mode can be
 * either 'default' (toggle only between stacked/tabbed/last_split_layout),
 * 'split' (toggle only between splitv/splith) or 'all' (toggle between all
 * layouts).
 *
 */
void con_toggle_layout(Con *con, const char *toggle_mode) {
    Con *parent = con;
    /* Users can focus workspaces, but not any higher in the hierarchy.
     * Focus on the workspace is a special case, since in every other case, the
     * user means "change the layout of the parent split container". */
    if (con->type != CT_WORKSPACE)
        parent = con->parent;
    DLOG("con_toggle_layout(%p, %s), parent = %p\n", con, toggle_mode, parent);

    if (strcmp(toggle_mode, "split") == 0) {
        /* Toggle between splits. When the current layout is not a split
         * layout, we just switch back to last_split_layout. Otherwise, we
         * change to the opposite split layout. */
        if (parent->layout != L_SPLITH && parent->layout != L_SPLITV)
            con_set_layout(con, parent->last_split_layout);
        else {
            if (parent->layout == L_SPLITH)
                con_set_layout(con, L_SPLITV);
            else con_set_layout(con, L_SPLITH);
        }
    } else {
        if (parent->layout == L_STACKED)
            con_set_layout(con, L_TABBED);
        else if (parent->layout == L_TABBED) {
            if (strcmp(toggle_mode, "all") == 0)
                con_set_layout(con, L_SPLITH);
            else con_set_layout(con, parent->last_split_layout);
        } else if (parent->layout == L_SPLITH || parent->layout == L_SPLITV) {
            if (strcmp(toggle_mode, "all") == 0) {
                /* When toggling through all modes, we toggle between
                 * splith/splitv, whereas normally we just directly jump to
                 * stacked. */
                if (parent->layout == L_SPLITH)
                    con_set_layout(con, L_SPLITV);
                else con_set_layout(con, L_STACKED);
            } else {
                con_set_layout(con, L_STACKED);
            }
        }
    }
}

/*
 * Callback which will be called when removing a child from the given con.
 * Kills the container if it is empty and replaces it with the child if there
 * is exactly one child.
 *
 */
static void con_on_remove_child(Con *con) {
    DLOG("on_remove_child\n");

    /* Every container 'above' (in the hierarchy) the workspace content should
     * not be closed when the last child was removed */
    if (con->type == CT_OUTPUT ||
        con->type == CT_ROOT ||
        con->type == CT_DOCKAREA) {
        DLOG("not handling, type = %d\n", con->type);
        return;
    }

    /* For workspaces, close them only if they're not visible anymore */
    if (con->type == CT_WORKSPACE) {
        if (TAILQ_EMPTY(&(con->focus_head)) && !workspace_is_visible(con)) {
            LOG("Closing old workspace (%p / %s), it is empty\n", con, con->name);
            tree_close(con, DONT_KILL_WINDOW, false, false);
            ipc_send_event("workspace", I3_IPC_EVENT_WORKSPACE, "{\"change\":\"empty\"}");
        }
        return;
    }

    con_force_split_parents_redraw(con);

    /* TODO: check if this container would swallow any other client and
     * don’t close it automatically. */
    int children = con_num_children(con);
    if (children == 0) {
        DLOG("Container empty, closing\n");
        tree_close(con, DONT_KILL_WINDOW, false, false);
        return;
    }
}

/*
 * Determines the minimum size of the given con by looking at its children (for
 * split/stacked/tabbed cons). Will be called when resizing floating cons
 *
 */
Rect con_minimum_size(Con *con) {
    DLOG("Determining minimum size for con %p\n", con);

    if (con_is_leaf(con)) {
        DLOG("leaf node, returning 75x50\n");
        return (Rect){ 0, 0, 75, 50 };
    }

    if (con->type == CT_FLOATING_CON) {
        DLOG("floating con\n");
        Con *child = TAILQ_FIRST(&(con->nodes_head));
        return con_minimum_size(child);
    }

    if (con->layout == L_STACKED || con->layout == L_TABBED) {
        uint32_t max_width = 0, max_height = 0, deco_height = 0;
        Con *child;
        TAILQ_FOREACH(child, &(con->nodes_head), nodes) {
            Rect min = con_minimum_size(child);
            deco_height += child->deco_rect.height;
            max_width = max(max_width, min.width);
            max_height = max(max_height, min.height);
        }
        DLOG("stacked/tabbed now, returning %d x %d + deco_rect = %d\n",
             max_width, max_height, deco_height);
        return (Rect){ 0, 0, max_width, max_height + deco_height };
    }

    /* For horizontal/vertical split containers we sum up the width (h-split)
     * or height (v-split) and use the maximum of the height (h-split) or width
     * (v-split) as minimum size. */
    if (con_is_split(con)) {
        uint32_t width = 0, height = 0;
        Con *child;
        TAILQ_FOREACH(child, &(con->nodes_head), nodes) {
            Rect min = con_minimum_size(child);
            if (con->layout == L_SPLITH) {
                width += min.width;
                height = max(height, min.height);
            } else {
                height += min.height;
                width = max(width, min.width);
            }
        }
        DLOG("split container, returning width = %d x height = %d\n", width, height);
        return (Rect){ 0, 0, width, height };
    }

    ELOG("Unhandled case, type = %d, layout = %d, split = %d\n",
         con->type, con->layout, con_is_split(con));
    assert(false);
}

/*
 * Returns true if changing the focus to con would be allowed considering
 * the fullscreen focus constraints. Specifically, if a fullscreen container or
 * any of its descendants is focused, this function returns true if and only if
 * focusing con would mean that focus would still be visible on screen, i.e.,
 * the newly focused container would not be obscured by a fullscreen container.
 *
 * In the simplest case, if a fullscreen container or any of its descendants is
 * fullscreen, this functions returns true if con is the fullscreen container
 * itself or any of its descendants, as this means focus wouldn't escape the
 * boundaries of the fullscreen container.
 *
 * In case the fullscreen container is of type CF_OUTPUT, this function returns
 * true if con is on a different workspace, as focus wouldn't be obscured by
 * the fullscreen container that is constrained to a different workspace.
 *
 * Note that this same logic can be applied to moving containers. If a
 * container can be focused under the fullscreen focus constraints, it can also
 * become a parent or sibling to the currently focused container.
 *
 */
bool con_fullscreen_permits_focusing(Con *con) {
    /* No focus, no problem. */
    if (!focused)
        return true;

    /* Find the first fullscreen ascendent. */
    Con *fs = focused;
    while (fs && fs->fullscreen_mode == CF_NONE)
        fs = fs->parent;

    /* fs must be non-NULL since the workspace con doesn’t have CF_NONE and
     * there always has to be a workspace con in the hierarchy. */
    assert(fs != NULL);
    /* The most common case is we hit the workspace level. In this
     * situation, changing focus is also harmless. */
    assert(fs->fullscreen_mode != CF_NONE);
    if (fs->type == CT_WORKSPACE)
        return true;

    /* Allow it if the container itself is the fullscreen container. */
    if (con == fs)
        return true;

    /* If fullscreen is per-output, the focus being in a different workspace is
     * sufficient to guarantee that change won't leave fullscreen in bad shape. */
    if (fs->fullscreen_mode == CF_OUTPUT &&
        con_get_workspace(con) != con_get_workspace(fs)) {
            return true;
    }

    /* Allow it only if the container to be focused is contained within the
     * current fullscreen container. */
    do {
        if (con->parent == fs)
            return true;
        con = con->parent;
    } while (con);

    /* Focusing con would hide it behind a fullscreen window, disallow it. */
    return false;
}

/*
 *
 * Checks if the given container has an urgent child.
 *
 */
bool con_has_urgent_child(Con *con) {
    Con *child;

    if (con_is_leaf(con))
        return con->urgent;

    /* We are not interested in floating windows since they can only be
     * attached to a workspace → nodes_head instead of focus_head */
    TAILQ_FOREACH(child, &(con->nodes_head), nodes) {
        if (con_has_urgent_child(child))
            return true;
    }

    return false;
}

/*
 * Make all parent containers urgent if con is urgent or clear the urgent flag
 * of all parent containers if there are no more urgent children left.
 *
 */
void con_update_parents_urgency(Con *con) {
    Con *parent = con->parent;

    bool new_urgency_value = con->urgent;
    while (parent && parent->type != CT_WORKSPACE && parent->type != CT_DOCKAREA) {
        if (new_urgency_value) {
            parent->urgent = true;
        } else {
            /* We can only reset the urgency when the parent
             * has no other urgent children */
            if (!con_has_urgent_child(parent))
                parent->urgent = false;
        }
        parent = parent->parent;
    }
}

/*
 * Create a string representing the subtree under con.
 *
 */
char *con_get_tree_representation(Con *con) {
    /* this code works as follows:
     *  1) create a string with the layout type (D/V/H/T/S) and an opening bracket
     *  2) append the tree representation of the children to the string
     *  3) add closing bracket
     *
     * The recursion ends when we hit a leaf, in which case we return the
     * class_instance of the contained window.
     */

    /* end of recursion */
    if (con_is_leaf(con)) {
        if (!con->window)
            return sstrdup("nowin");

        if (!con->window->class_instance)
            return sstrdup("noinstance");

        return sstrdup(con->window->class_instance);
    }

    char *buf;
    /* 1) add the Layout type to buf */
    if (con->layout == L_DEFAULT)
        buf = sstrdup("D[");
    else if (con->layout == L_SPLITV)
        buf = sstrdup("V[");
    else if (con->layout == L_SPLITH)
        buf = sstrdup("H[");
    else if (con->layout == L_TABBED)
        buf = sstrdup("T[");
    else if (con->layout == L_STACKED)
        buf = sstrdup("S[");
    else {
        ELOG("BUG: Code not updated to account for new layout type\n");
        assert(false);
    }

    /* 2) append representation of children */
    Con *child;
    TAILQ_FOREACH(child, &(con->nodes_head), nodes) {
        char *child_txt = con_get_tree_representation(child);

        char *tmp_buf;
        sasprintf(&tmp_buf, "%s%s%s", buf,
                (TAILQ_FIRST(&(con->nodes_head)) == child ? "" : " "), child_txt);
        free(buf);
        buf = tmp_buf;
    }

    /* 3) close the brackets */
    char *complete_buf;
    sasprintf(&complete_buf, "%s]", buf);
    free(buf);

    return complete_buf;
}