commands/move: unwrap workspace container on move to new workspace

If moving e.g. `T[app app]` into a new workspace with `workspace_layout
tabbed`, then post-move the tree in that workspace will be `T[T[app
app]]`. This still happens with horizontal or vertical workspace layout,
but is less visible since those containers have no decorations.

Fixes #5426.

(cherry picked from commit 92891fb1edef5136ae4eb35fec5b8523f031be81)

3 files changed, 25 insertions, 3 deletions

diff --git a/include/sway/tree/workspace.h b/include/sway/tree/workspace.h
index 41b59796..1adbe68a 100644
--- a/include/sway/tree/workspace.h
+++ b/include/sway/tree/workspace.h
@@ -105,6 +105,9 @@ struct sway_container *workspace_find_container(struct sway_workspace *ws,
  */
 struct sway_container *workspace_wrap_children(struct sway_workspace *ws);
 
+void workspace_unwrap_children(struct sway_workspace *ws,
+                struct sway_container *wrap);
+
 void workspace_detach(struct sway_workspace *workspace);
 
 void workspace_add_tiling(struct sway_workspace *workspace,
diff --git a/sway/commands/move.c b/sway/commands/move.c
index cdbad13e..5851520e 100644
--- a/sway/commands/move.c
+++ b/sway/commands/move.c
@@ -208,9 +208,13 @@ static void container_move_to_workspace(struct sway_container *container,
                 }
         } else {
                 container_detach(container);
-                container->width = container->height = 0;
-                container->width_fraction = container->height_fraction = 0;
-                workspace_add_tiling(workspace, container);
+                if (workspace_is_empty(workspace) && container->children) {
+                        workspace_unwrap_children(workspace, container);
+                } else {
+                        container->width = container->height = 0;
+                        container->width_fraction = container->height_fraction = 0;
+                        workspace_add_tiling(workspace, container);
+                }
                 container_update_representation(container);
         }
         if (container->view) {
diff --git a/sway/tree/workspace.c b/sway/tree/workspace.c
index 0fa28951..3bcba8e5 100644
--- a/sway/tree/workspace.c
+++ b/sway/tree/workspace.c
@@ -641,6 +641,21 @@ struct sway_container *workspace_wrap_children(struct sway_workspace *ws) {
         return middle;
 }
 
+void workspace_unwrap_children(struct sway_workspace *ws,
+                struct sway_container *wrap) {
+        if (!sway_assert(workspace_is_empty(ws),
+                        "target workspace must be empty")) {
+                return;
+        }
+
+        ws->layout = wrap->layout;
+        while (wrap->children->length) {
+                struct sway_container *child = wrap->children->items[0];
+                container_detach(child);
+                workspace_add_tiling(ws, child);
+        }
+}
+
 void workspace_detach(struct sway_workspace *workspace) {
         struct sway_output *output = workspace->output;
         int index = list_find(output->workspaces, workspace);