[gtk+/gtk-3-22] combobox: Work around popup handler altering model

[Daniel Boles <dboles src gnome org>]

commit e98e6f73be8ec7647d6eddeacf6d13cd96352589
Author: Daniel Boles <dboles src gnome org>
Date:   Wed Jan 18 22:22:52 2017 +0000

    combobox: Work around popup handler altering model
    
    GtkFileChooserButton installs a handler for the popped-up signal, which
    refilters the menu, in order to hide the “(None)” item from the popup
    if it was previously selected in the ComboBox. This oddity means that:
    
     • Until recently, this item would be selected in the menu shell, which
       would then be popped up and change the selection away from that item.
       This was therefore redundant (more on which below!) but benign.
    
     • After the patch for https://bugzilla.gnome.org/show_bug.cgi?id=771242
       however, this causes a critical assertion fail, as now we stash the
       originally selected item in a pointer so that it can be selected only
       after realisation/popup – but by that stage, the model has just been
       refiltered and the previous pointer no longer refers to a valid item.
    
    This commit works around this problem by, after popping up the menu,
    getting the active item again, in case a popped-up handler has gone and
    invalidated the pointer to the active item that we saved before popup.
    
    If a handler does this, everything done to find/use the original item is
    pointless. But this avoids the ugly critical in FileChooserButton, while
    not harming every other ComboBox that doesn’t mess with its model while
    popping up (hopefully the vast majority), and it’s very difficult to
    imagine a way to check if the active item is /going to/ be hidden later)

 gtk/gtkcombobox.c |   10 +++++++---
 1 files changed, 7 insertions(+), 3 deletions(-)
---
diff --git a/gtk/gtkcombobox.c b/gtk/gtkcombobox.c
index 4b10659..c63e98c 100644
--- a/gtk/gtkcombobox.c
+++ b/gtk/gtkcombobox.c
@@ -2174,7 +2174,6 @@ gtk_combo_box_menu_popup (GtkComboBox    *combo_box,
     {
       /* FIXME handle nested menus better */
       GtkWidget *active = gtk_menu_get_active (GTK_MENU (priv->popup_widget));;
-      GtkWidget *select = active;
       gint rect_anchor_dy = -2;
       GList *i;
       GtkWidget *child;
@@ -2226,8 +2225,13 @@ gtk_combo_box_menu_popup (GtkComboBox    *combo_box,
                                 GDK_GRAVITY_NORTH_WEST,
                                 trigger_event);
 
-      if (select)
-        gtk_menu_shell_select_item (GTK_MENU_SHELL (priv->popup_widget), select);
+      /* As a hack, re-get the active item, in case a popup handler, like that
+       * of FileChooserButton, just caused the menu to be refiltered, making the
+       * previous active item pointer invalid now. This seems pretty ugly and
+       * makes the y-offset loop pointless for such cases, so FIXME later? */
+      active = gtk_menu_get_active (GTK_MENU (priv->popup_widget));
+      if (active)
+        gtk_menu_shell_select_item (GTK_MENU_SHELL (priv->popup_widget), active);
     }
 }