kiosk-shell: Favor out views on same output

In multiple output cases, finding the succesor from the inactive layer
might result in picking the wrong view when there are multiple views
being stacked in the inactive layer. This adds two additional checks to
favor views on the same output as the one being destroyed/removed.

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>

kiosk-shell/kiosk-shell.c

@@ -650,12 +650,18 @@ find_focus_successor(struct weston_layer *layer,
 	struct weston_view *top_view = NULL;
 	struct weston_view *view;
 
+
 	/* we need to take into account that the surface being destroyed it not
 	 * always the same as the focus_surface, which could result in picking
 	 * and *activating* the wrong window, so avoid returning a view for
 	 * that case. A particular case is when a top-level child window, would
-	 * pick a parent window below the focused_surface. */
-	if (focused_surface != shsurf->view->surface)
+	 * pick a parent window below the focused_surface.
+	 *
+	 * Apply that only on the same output to avoid incorrectly returning an
+	 * invalid/empty view, which could happen if the view being destroyed
+	 * is on a output different than the focused_surface output */
+	if (focused_surface && focused_surface != shsurf->view->surface &&
+	    shsurf->output == focused_surface->output)
 		return top_view;
 
 	wl_list_for_each(view, &layer->view_list.link, layer_link.link) {
@@ -665,6 +671,10 @@ find_focus_successor(struct weston_layer *layer,
 		if (!view->is_mapped || view == shsurf->view)
 			continue;
 
+		/* pick views only on the same output */
+		if (view->output != shsurf->output)
+			continue;
+
 		view_shsurf = get_kiosk_shell_surface(view->surface);
 		if (!view_shsurf)
 			continue;