[libpanel] frame: restore visible child in case it changes

[Christian Hergert <chergert src gnome org>]

commit 7b49990e20b256dfc58309f933db43c861e567b5
Author: Christian Hergert <chergert redhat com>
Date:   Fri Sep 16 22:05:05 2022 -0700

    frame: restore visible child in case it changes

 src/panel-frame.c | 9 +++++++++
 1 file changed, 9 insertions(+)
---
diff --git a/src/panel-frame.c b/src/panel-frame.c
index 9e60b6a..eac48b2 100644
--- a/src/panel-frame.c
+++ b/src/panel-frame.c
@@ -960,6 +960,7 @@ panel_frame_remove (PanelFrame  *self,
                     PanelWidget *panel)
 {
   PanelFramePrivate *priv = panel_frame_get_instance_private (self);
+  PanelWidget *old_visible_child;
   GtkWidget *dock_child;
   GtkWidget *grid;
   AdwTabPage *page;
@@ -967,6 +968,11 @@ panel_frame_remove (PanelFrame  *self,
   g_return_if_fail (PANEL_IS_FRAME (self));
   g_return_if_fail (PANEL_IS_WIDGET (panel));
 
+  old_visible_child = panel_frame_get_visible_child (self);
+
+  if (old_visible_child == panel)
+    old_visible_child = NULL;
+
   page = adw_tab_view_get_page (priv->tab_view, GTK_WIDGET (panel));
   adw_tab_view_close_page (priv->tab_view, page);
 
@@ -981,6 +987,9 @@ panel_frame_remove (PanelFrame  *self,
         }
     }
 
+  if (old_visible_child != NULL)
+    panel_frame_set_visible_child (self, old_visible_child);
+
   if ((grid = gtk_widget_get_ancestor (GTK_WIDGET (self), PANEL_TYPE_GRID)))
     _panel_grid_update_closeable (PANEL_GRID (grid));