[gnome-control-center] wacom: Clear background on "target" actor in calibration UI

[Carlos Garnacho <carlosg src gnome org>]

commit 71945b815653954a5418a3df077903e61127b134
Author: Carlos Garnacho <carlosg gnome org>
Date:   Fri Nov 29 15:33:36 2013 +0100

    wacom: Clear background on "target" actor in calibration UI
    
    the actor's draw() method isn't guaranteed to get a pristine surface,
    which may cause artifacts if the background is left untouched, so
    clear the background each time the actor has to be drawn.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=719701

 panels/wacom/calibrator/cc-target-actor.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/panels/wacom/calibrator/cc-target-actor.c b/panels/wacom/calibrator/cc-target-actor.c
index a0961c6..8bf64cc 100644
--- a/panels/wacom/calibrator/cc-target-actor.c
+++ b/panels/wacom/calibrator/cc-target-actor.c
@@ -106,6 +106,10 @@ draw_target (ClutterCairoTexture *texture,
              gint                 height,
              gpointer             data)
 {
+  cairo_set_operator (cr, CAIRO_OPERATOR_CLEAR);
+  cairo_paint (cr);
+
+  cairo_set_operator (cr, CAIRO_OPERATOR_OVER);
   cairo_set_source_rgb(cr, 1.0, 1.0, 1.0);
 
   cairo_set_line_width(cr, 1);