[gimp] libgimpwidgets: invalidate the rulers' backdrop when the widget style is changed

[N/A <ell src gnome org>]

commit 2cb26a040a414cd577fc2458c2025845c3c41b4a
Author: Ell <ell_se yahoo com>
Date:   Mon Feb 27 05:03:59 2017 -0500

    libgimpwidgets: invalidate the rulers' backdrop when the widget style is changed
    
    ... in particular, when swithcing themes.
    
    Otherwise, the rulers keep their old, mismatched, style, until the
    ticks are updated.

 libgimpwidgets/gimpruler.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/libgimpwidgets/gimpruler.c b/libgimpwidgets/gimpruler.c
index 28b428a..6b554c3 100644
--- a/libgimpwidgets/gimpruler.c
+++ b/libgimpwidgets/gimpruler.c
@@ -921,6 +921,8 @@ gimp_ruler_style_set (GtkWidget *widget,
                         "font-scale", &priv->font_scale,
                         NULL);
 
+  priv->backing_store_valid = FALSE;
+
   if (priv->layout)
     {
       g_object_unref (priv->layout);