[mutter] window: Ignore requests to be placed on non-existent workspaces

[Carlos Garnacho <carlosg src gnome org>]

commit aa0aa89a1e665b92835828f28f0f54104bde1471
Author: Florian Müllner <fmuellner gnome org>
Date:   Mon Feb 3 22:58:38 2020 +0100

    window: Ignore requests to be placed on non-existent workspaces
    
    When an X11 window requests an initial workspace, we currently trust
    it that the workspace actually exists. However dynamic workspaces
    make this easy to get wrong for applications: They make it likely
    for the number of workspaces to change between application starts,
    and if the app blindly applies its saved state on startup, it will
    trigger an assertion.
    
    Make sure that we pass valid parameters to set_workspace_state(),
    and simply let the workspace assignment fall through to the default
    handling otherwise.
    
    https://gitlab.gnome.org/GNOME/mutter/issues/1029

 src/core/window.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
---
diff --git a/src/core/window.c b/src/core/window.c
index d7d3e1b59..d5c92102b 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -1288,7 +1288,10 @@ _meta_window_shared_new (MetaDisplay         *display,
                                                                      window->initial_workspace);
         }
 
-      set_workspace_state (window, on_all_workspaces, workspace);
+      /* Ignore when a window requests to be placed on a non-existent workspace
+       */
+      if (on_all_workspaces || workspace != NULL)
+        set_workspace_state (window, on_all_workspaces, workspace);
     }
 
   /* override-redirect windows are subtly different from other windows