Bugfix: properly react to windows being unmapped before we can reparent (Thanks xeen...

We need to verify that setting the event mask works, and we need to
include StructureNotify to get unmap events at any point in time.
Thanks darkraven for the pointer.

fixes #718

diff --git a/src/manage.c b/src/manage.c
index 9a5a4cf39555df2e4f5130959c93ead9bcba7e31..d3f5ca8dfd98bdd8506c89759fb5ef2fda8af723 100644 (file)
--- a/src/manage.c
+++ b/src/manage.c
@@ -126,11 +126,22 @@ void manage_window(xcb_window_t window, xcb_get_window_attributes_cookie_t cooki
     uint32_t values[1];
 
     /* Set a temporary event mask for the new window, consisting only of
-     * PropertyChange. We need to be notified of PropertyChanges because the
-     * client can change its properties *after* we requested them but *before*
-     * we actually reparented it and have set our final event mask. */
-    values[0] = XCB_EVENT_MASK_PROPERTY_CHANGE;
-    xcb_change_window_attributes(conn, window, XCB_CW_EVENT_MASK, values);
+     * PropertyChange and StructureNotify. We need to be notified of
+     * PropertyChanges because the client can change its properties *after* we
+     * requested them but *before* we actually reparented it and have set our
+     * final event mask.
+     * We need StructureNotify because the client may unmap the window before
+     * we get to re-parent it.
+     * If this request fails, we assume the client has already unmapped the
+     * window between the MapRequest and our event mask change. */
+    values[0] = XCB_EVENT_MASK_PROPERTY_CHANGE |
+                XCB_EVENT_MASK_STRUCTURE_NOTIFY;
+    xcb_void_cookie_t event_mask_cookie =
+        xcb_change_window_attributes_checked(conn, window, XCB_CW_EVENT_MASK, values);
+    if (xcb_request_check(conn, event_mask_cookie) != NULL) {
+        LOG("Could not change event mask, the window probably already disappeared.\n");
+        goto out;
+    }
 
 #define GET_PROPERTY(atom, len) xcb_get_property(conn, false, window, atom, XCB_GET_PROPERTY_TYPE_ANY, 0, len)