[gnome-control-center/gnome-3-28] shell: Only try to select an existing panel on startup

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 73c40aa3a7e48818c6af5ea1188a933c550eddcb
Author: Benjamin Berg <bberg redhat com>
Date:   Wed Apr 25 10:32:10 2018 +0200

    shell: Only try to select an existing panel on startup
    
    When selecting the panel on startup based on the "last-panel" settings,
    we need to make sure that the panel exists.
    
    Note that this is a special case which does not use the internal
    set_active_panel_from_id API. Using it is currently not possible because
    the API does not report back the error and we would end up not selecting
    any panel.
    
    
    (cherry picked from commit f547d9129d6d69c0eacd24cef7cda7eca09d6106)

 shell/cc-shell-model.c | 24 ++++++++++++++++++++++++
 shell/cc-shell-model.h |  3 +++
 shell/cc-window.c      |  2 +-
 3 files changed, 28 insertions(+), 1 deletion(-)
---
diff --git a/shell/cc-shell-model.c b/shell/cc-shell-model.c
index 55f3e3c82..2a69d6a12 100644
--- a/shell/cc-shell-model.c
+++ b/shell/cc-shell-model.c
@@ -327,6 +327,30 @@ cc_shell_model_add_item (CcShellModel    *model,
   g_strfreev (keywords);
 }
 
+gboolean
+cc_shell_model_has_panel (CcShellModel *model,
+                          const char   *id)
+{
+  GtkTreeIter iter;
+  gboolean valid;
+
+  g_assert (id);
+
+  valid = gtk_tree_model_get_iter_first (model, &iter);
+  while (valid)
+    {
+      g_autofree gchar *panel_id = NULL;
+
+      gtk_tree_model_get (model, &iter, COL_ID, &panel_id, -1);
+      if (g_str_equal (id, panel_id))
+        return TRUE;
+
+      valid = gtk_tree_model_iter_next (model, &iter);
+    }
+
+  return FALSE;
+}
+
 gboolean
 cc_shell_model_iter_matches_search (CcShellModel *model,
                                     GtkTreeIter  *iter,
diff --git a/shell/cc-shell-model.h b/shell/cc-shell-model.h
index 259407109..4ba8342e5 100644
--- a/shell/cc-shell-model.h
+++ b/shell/cc-shell-model.h
@@ -98,6 +98,9 @@ void cc_shell_model_add_item (CcShellModel   *model,
                               GAppInfo       *appinfo,
                               const char     *id);
 
+gboolean cc_shell_model_has_panel (CcShellModel *model,
+                                   const char   *id);
+
 gboolean cc_shell_model_iter_matches_search (CcShellModel *model,
                                              GtkTreeIter  *iter,
                                              const char   *term);
diff --git a/shell/cc-window.c b/shell/cc-window.c
index 557819e0c..9144834a4 100644
--- a/shell/cc-window.c
+++ b/shell/cc-window.c
@@ -743,7 +743,7 @@ cc_window_init (CcWindow *self)
   /* After everything is loaded, select the last used panel, if any,
    * or the first visible panel */
   id = g_settings_get_string (self->settings, "last-panel");
-  if (id != NULL && *id != '\0')
+  if (id != NULL && cc_shell_model_has_panel (self->store, id))
     cc_panel_list_set_active_panel (CC_PANEL_LIST (self->panel_list), id);
   else
     cc_panel_list_activate (CC_PANEL_LIST (self->panel_list));