workspace_move_to_output: Avoid operations when workspace already at destination

Closes #3635.
Probably the bug can still happen when a tree_close_internal happens
inside a workspace_show but modifying the code to avoid them seems to
not be worth it.

diff --git a/src/workspace.c b/src/workspace.c
index 0aeecb456455208f5fa1b74abd15de9060f11217..3cf7475424b9015d76fded271fdb06261de842b4 100644 (file)
--- a/src/workspace.c
+++ b/src/workspace.c
@@ -969,6 +969,11 @@ void workspace_move_to_output(Con *ws, Output *output) {
     Con *content = output_get_content(output->con);
     DLOG("got output %p with content %p\n", output, content);
 
+    if (ws->parent == content) {
+        DLOG("Nothing to do, workspace already there\n");
+        return;
+    }
+
     Con *previously_visible_ws = TAILQ_FIRST(&(content->focus_head));
     if (previously_visible_ws) {
         DLOG("Previously visible workspace = %p / %s\n", previously_visible_ws, previously_visible_ws->name);