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, 2 insertions, 1 deletions

diff --git a/sway/commands/split.c b/sway/commands/split.c
index e9670722..8702f39e 100644
--- a/sway/commands/split.c
+++ b/sway/commands/split.c
@@ -13,7 +13,8 @@ static struct cmd_results *do_split(int layout) {
         struct sway_container *con = config->handler_context.container;
         struct sway_workspace *ws = config->handler_context.workspace;
         if (con) {
-                if (container_is_scratchpad_hidden(con)) {
+                if (container_is_scratchpad_hidden(con) &&
+                                con->fullscreen_mode != FULLSCREEN_GLOBAL) {
                         return cmd_results_new(CMD_FAILURE,
                                         "Cannot split a hidden scratchpad container");
                 }