[gtk: 2/3] popover: Cycle around focus with (Shift+)Tab

[Matthias Clasen <matthiasc src gnome org>]

commit a3ce5741930c8599ee939ee0d656fbb21bf7e41a
Author: vanadiae <vanadiae35 gmail com>
Date:   Mon Jul 5 19:33:08 2021 +0200

    popover: Cycle around focus with (Shift+)Tab
    
    Same thing as the previous popovermenu commit, except for the base popover
    because the popovermenu needs special behaviour with e.g. sides arrow so
    we need to have the "cycle around" for regular popovers here too.

 gtk/gtkpopover.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 56 insertions(+), 2 deletions(-)
---
diff --git a/gtk/gtkpopover.c b/gtk/gtkpopover.c
index 4a6bd4074e..706afc9108 100644
--- a/gtk/gtkpopover.c
+++ b/gtk/gtkpopover.c
@@ -972,6 +972,59 @@ gtk_popover_unrealize (GtkWidget *widget)
   g_clear_object (&priv->surface);
 }
 
+static gboolean
+gtk_popover_focus (GtkWidget        *widget,
+                   GtkDirectionType  direction)
+{
+  if (!gtk_widget_get_visible (widget))
+    return FALSE;
+
+  /* This code initially comes from gtkpopovermenu.c */
+  if (gtk_widget_get_first_child (widget) == NULL)
+    {
+      /* Empty popover, so nothing to Tab through. */
+      return FALSE;
+    }
+  else
+    {
+      /* Move focus normally, but when nothing can be focused in this direction then we cycle around. */
+      if (gtk_widget_focus_move (widget, direction))
+        return TRUE;
+
+      if (gtk_popover_get_autohide (GTK_POPOVER (widget)))
+        {
+          GtkWidget *p = gtk_root_get_focus (gtk_widget_get_root (widget));
+
+          /* In the case where the popover doesn't have any focusable child (like
+           * the GtkTreePopover for combo boxes) then the focus will end up out of
+           * the popover, hence creating an infinite loop below. To avoid this, just
+           * say we had focus and stop here.
+           */
+          if (!gtk_widget_is_ancestor (p, widget) && p != widget)
+            return TRUE;
+
+          /* Cycle around with (Shift+)Tab */
+          if (direction == GTK_DIR_TAB_FORWARD || direction == GTK_DIR_TAB_BACKWARD)
+            {
+              for (;
+                   p != widget;
+                   p = gtk_widget_get_parent (p))
+                {
+                  /* Unfocus everything in the popover. */
+                  gtk_widget_set_focus_child (p, NULL);
+                }
+            }
+          /* Focus again from scratch */
+          gtk_widget_focus_move (widget, direction);
+          return TRUE;
+        }
+      else
+        {
+          return FALSE;
+        }
+    }
+}
+
 static void
 gtk_popover_show (GtkWidget *widget)
 {
@@ -1734,6 +1787,7 @@ gtk_popover_class_init (GtkPopoverClass *klass)
   widget_class->unrealize = gtk_popover_unrealize;
   widget_class->map = gtk_popover_map;
   widget_class->unmap = gtk_popover_unmap;
+  widget_class->focus = gtk_popover_focus;
   widget_class->show = gtk_popover_show;
   widget_class->hide = gtk_popover_hide;
   widget_class->measure = gtk_popover_measure;
@@ -2175,8 +2229,8 @@ gtk_popover_get_position (GtkPopover *popover)
  * Sets whether @popover is modal.
  *
  * A modal popover will grab the keyboard focus on it when being
- * displayed. Clicking outside the popover area or pressing Esc
- * will dismiss the popover.
+ * displayed. Focus will wrap around within the popover. Clicking
+ * outside the popover area or pressing Esc will dismiss the popover.
  *
  * Called this function on an already showing popup with a new
  * autohide value different from the current one, will cause the