[gtk] colorscale: Redraw correct widget after setting rgba

[Timm Bäder <baedert src gnome org>]

commit 9b15c6900a4d3b6bfa89611754317ee7402e9de6
Author: Timm Bäder <mail baedert org>
Date:   Wed Jan 16 19:20:53 2019 +0100

    colorscale: Redraw correct widget after setting rgba
    
    The entire color scale hack is still done in GtkRange, which draws the
    color scale in the range gizmo. So, to correctly redraw the color scale
    when setting a new color, we need to redraw the proper widget and that's
    the trough widget.
    
    Fixes #1453

 gtk/gtkcolorscale.c   | 2 +-
 gtk/gtkrange.c        | 8 ++++++++
 gtk/gtkrangeprivate.h | 2 ++
 3 files changed, 11 insertions(+), 1 deletion(-)
---
diff --git a/gtk/gtkcolorscale.c b/gtk/gtkcolorscale.c
index 40cc3e05d3..c5b7d3046a 100644
--- a/gtk/gtkcolorscale.c
+++ b/gtk/gtkcolorscale.c
@@ -289,7 +289,7 @@ gtk_color_scale_set_rgba (GtkColorScale *scale,
   GtkColorScalePrivate *priv = gtk_color_scale_get_instance_private (scale);
 
   priv->color = *color;
-  gtk_widget_queue_draw (GTK_WIDGET (scale));
+  gtk_widget_queue_draw (gtk_range_get_trough_widget (GTK_RANGE (scale)));
 }
 
 GtkWidget *
diff --git a/gtk/gtkrange.c b/gtk/gtkrange.c
index d745e93174..dcd6b95899 100644
--- a/gtk/gtkrange.c
+++ b/gtk/gtkrange.c
@@ -2948,6 +2948,14 @@ gtk_range_get_slider_widget (GtkRange *range)
   return priv->slider_widget;
 }
 
+GtkWidget *
+gtk_range_get_trough_widget (GtkRange *range)
+{
+  GtkRangePrivate *priv = gtk_range_get_instance_private (range);
+
+  return priv->trough_widget;
+}
+
 void
 gtk_range_start_autoscroll (GtkRange      *range,
                             GtkScrollType  scroll_type)
diff --git a/gtk/gtkrangeprivate.h b/gtk/gtkrangeprivate.h
index f76116ea10..40ee468b9c 100644
--- a/gtk/gtkrangeprivate.h
+++ b/gtk/gtkrangeprivate.h
@@ -42,6 +42,8 @@ gint               _gtk_range_get_stop_positions           (GtkRange      *range
                                                             gint         **values);
 
 GtkWidget         *gtk_range_get_slider_widget             (GtkRange *range);
+GtkWidget         *gtk_range_get_trough_widget             (GtkRange *range);
+
 
 void               gtk_range_start_autoscroll              (GtkRange      *range,
                                                             GtkScrollType  scroll_type);