[gtkhtml/gnome-3-4] Bug 672582 - Fix selection behavior inside <iframe>

[Matthew Barnes <mbarnes src gnome org>]

commit 9ec36544203d4c1b98aa843c2c3ff0a4f725da68
Author: Sam Thursfield <sam thursfield codethink co uk>
Date:   Thu May 3 15:04:20 2012 -0400

    Bug 672582 - Fix selection behavior inside <iframe>
    
    Since kinetic scrolling was introduced in Gtk+, GtkScrolledWindow
    has had its own GdkWindow. This means we need to use the allocation
    of the GtkScrolledWindow rather than its child GtkHTML widget when we
    want to translate pointer coordinates relative to the iframe, because
    a widget's GtkAllocation is relative to the parent GdkWindow.
    
    (cherry picked from commit 7b7b37745d2f46914be314e4d7aef7a575529345)

 gtkhtml/gtkhtml.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)
---
diff --git a/gtkhtml/gtkhtml.c b/gtkhtml/gtkhtml.c
index 697b16e..6284855 100644
--- a/gtkhtml/gtkhtml.c
+++ b/gtkhtml/gtkhtml.c
@@ -1823,9 +1823,14 @@ shift_to_iframe_parent (GtkWidget *widget,
                         gint *y)
 {
 	while (GTK_HTML (widget)->iframe_parent) {
+		GtkWidget *scrolled_window;
 		GtkAllocation allocation;
 
-		gtk_widget_get_allocation (widget, &allocation);
+		scrolled_window = gtk_widget_get_parent (widget);
+
+		g_return_val_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window), widget);
+
+		gtk_widget_get_allocation (scrolled_window, &allocation);
 
 		if (x)
 			*x += allocation.x - GTK_HTML (widget)->engine->x_offset;