Fix scratchpad fullscreen behavior and crash

When setting fullscreen on a hidden scratchpad container, there was a
check to see if there was an existing fullscreen container on the
workspace so it could be fullscreen disabled first. Since the workspace
is NULL, it would cause a SIGSEGV. This adds a NULL check to avoid the
crash.

This also changes the behavior of how fullscreen is handled when adding
a container to the scratchpad or changing visibility of a scratchpad
container to match i3's. The behavior is as follows:
- When adding a container to the scratchpad or hiding a container back
  into the scratchpad, there is an implicit fullscreen disable
- When setting fullscreen on a container that is hidden in the
  scratchpad, it will be fullscreen when shown (and fullscreen disabled
  when hidden as stated above)
- When setting fullscreen global on a container that is hidden in the
  scratchpad, it will be shown immediately as fullscreen global. The
  container is not moved to a workspace and remains in the
  scratchpad. The container will be visible until fullscreen disabled
  or killed. Since the container is in the scratchpad, running
  `scratchpad show` or `move container to scratchpad` will have no
  effect

This also changes `container_replace` to transfer fullscreen and
scratchpad status.

1 files changed, 7 insertions, 0 deletions

diff --git a/sway/commands/fullscreen.c b/sway/commands/fullscreen.c
index 52248ce4..a268ba03 100644
--- a/sway/commands/fullscreen.c
+++ b/sway/commands/fullscreen.c
@@ -26,6 +26,13 @@ struct cmd_results *cmd_fullscreen(int argc, char **argv) {
 				"Can't fullscreen an empty workspace");
 	}
 
+	// If in the scratchpad, operate on the highest container
+	if (container && !container->workspace) {
+		while (container->parent) {
+			container = container->parent;
+		}
+	}
+
 	bool is_fullscreen = container &&
 		container->fullscreen_mode != FULLSCREEN_NONE;
 	bool global = false;