[gtk] flowbox: Implement get_child_at_pos properly

[Timm Bäder <baedert src gnome org>]

commit c9d9f8b750dc9672c8bc899b0ba3b6f87d918e1e
Author: Timm Bäder <mail baedert org>
Date:   Thu Feb 14 07:11:34 2019 +0100

    flowbox: Implement get_child_at_pos properly
    
    With transforms in the mix, checking if the coordinate is inside the
    widget "allocation" makes even less sense. Just use gtk_widget_pick()
    and walk up until we find a GtkFlowBoxChild.

 gtk/gtkflowbox.c | 22 +++++-----------------
 1 file changed, 5 insertions(+), 17 deletions(-)
---
diff --git a/gtk/gtkflowbox.c b/gtk/gtkflowbox.c
index f95d8734e1..65c491fe4b 100644
--- a/gtk/gtkflowbox.c
+++ b/gtk/gtkflowbox.c
@@ -3918,7 +3918,7 @@ gtk_flow_box_get_child_at_index (GtkFlowBox *box,
  * @y: the y coordinate of the child
  *
  * Gets the child in the (@x, @y) position. Both @x and @y are
- * assumed to be relative to the allocation of @box.
+ * assumed to be relative to the origin of @box.
  *
  * Returns: (transfer none) (nullable): the child widget, which will
  *     always be a #GtkFlowBoxChild or %NULL in case no child widget
@@ -3929,24 +3929,12 @@ gtk_flow_box_get_child_at_pos (GtkFlowBox *box,
                                gint        x,
                                gint        y)
 {
-  GtkWidget *child;
-  GSequenceIter *iter;
-  GtkAllocation allocation;
-
-  for (iter = g_sequence_get_begin_iter (BOX_PRIV (box)->children);
-       !g_sequence_iter_is_end (iter);
-       iter = g_sequence_iter_next (iter))
-    {
-      child = g_sequence_get (iter);
-      if (!child_is_visible (child))
-        continue;
+  GtkWidget *child = gtk_widget_pick (GTK_WIDGET (box), x, y);
 
-      gtk_widget_get_allocation (child, &allocation);
-      if (gdk_rectangle_contains_point (&allocation, x, y))
-        return GTK_FLOW_BOX_CHILD (child);
-    }
+  if (!child)
+    return NULL;
 
-  return NULL;
+  return (GtkFlowBoxChild *)gtk_widget_get_ancestor (child, GTK_TYPE_FLOW_BOX_CHILD);
 }
 
 /**