fix layout switching (was broken because of workspace_layout)

For workspace containers, swayc_change_layout also changes ->layout alongside
->workspace_layout when it's a sensible thing to do. There is an additional test
for 'layout toggle' command which ensures that containers will be tiled
horizontally after toggling from tabbed or stacked.

include/sway/container.h

@@ -324,7 +324,7 @@ void close_views(swayc_t *container);
 
 /**
  * Assign layout to a container. Needed due to workspace container specifics.
- * Workspace always needs L_HORIZ layout.
+ * Workspace should always have either L_VERT or L_HORIZ layout.
  */
 swayc_t *swayc_change_layout(swayc_t *container, enum swayc_layouts layout);
 

sway/commands/layout.c

@@ -49,7 +49,7 @@ struct cmd_results *cmd_layout(int argc, char **argv) {
 		} else if (strcasecmp(argv[0], "splitv") == 0) {
 			swayc_change_layout(parent, L_VERT);
 		} else if (strcasecmp(argv[0], "toggle") == 0 && argc == 2 && strcasecmp(argv[1], "split") == 0) {
-			if (parent->layout == L_HORIZ) {
+			if (parent->layout == L_HORIZ && (parent->workspace_layout == L_NONE || parent->workspace_layout == L_HORIZ)) {
 				swayc_change_layout(parent, L_VERT);
 			} else {
 				swayc_change_layout(parent, L_HORIZ);

sway/container.c

@@ -950,6 +950,9 @@ swayc_t *swayc_tabbed_stacked_parent(swayc_t *con) {
 swayc_t *swayc_change_layout(swayc_t *container, enum swayc_layouts layout) {
 	if (container->type == C_WORKSPACE) {
 		container->workspace_layout = layout;
+    if (layout == L_HORIZ || layout == L_VERT) {
+      container->layout = layout;
+    }
 	} else {
 		container->layout = layout;
 	}