[gimp] app: increase GimpSelectionTools idle priority to avoid flickering

[Ell <ell src gnome org>]

commit 3369958525bd301cd3887dd55c354593d07fba54
Author: Ell <ell_se yahoo com>
Date:   Thu Apr 25 09:51:38 2019 -0400

    app: increase GimpSelectionTools idle priority to avoid flickering
    
    In gimp_selection_tool_start_change(), increase the priority of the
    idle source used for hiding the selection so that it's run before
    the canvas is redrawn, to avoid flickering the previous selection.

 app/tools/gimpselectiontool.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/app/tools/gimpselectiontool.c b/app/tools/gimpselectiontool.c
index 018534261c..45192e0799 100644
--- a/app/tools/gimpselectiontool.c
+++ b/app/tools/gimpselectiontool.c
@@ -708,9 +708,10 @@ gimp_selection_tool_start_change (GimpSelectionTool *sel_tool,
            * restarting the selection if we don't visit the main loop between
            * the start_change() and end_change() calls.
            */
-          sel_tool->idle_id = g_idle_add (
+          sel_tool->idle_id = g_idle_add_full (
+            G_PRIORITY_HIGH_IDLE,
             (GSourceFunc) gimp_selection_tool_idle,
-            sel_tool);
+            sel_tool, NULL);
         }
     }