[gimp/gimp-2-10] app: in the selection tools, blink mode box when the current operation is invalid

[Ell <ell src gnome org>]

commit 02ccab9e7e71c27bb805b45390490e756061495b
Author: Ell <ell_se yahoo com>
Date:   Mon Dec 10 07:42:52 2018 -0500

    app: in the selection tools, blink mode box when the current operation is invalid
    
    In the selection tools, when the selected operation is invalid,
    i.e., when trying to subtract-from or intersect-with an empty
    selection, blink the selection-mode box widget in the tool options,
    in addition to showing an error message in the status bar, to hint
    at the source of the error.
    
    (cherry picked from commit f990e416097becee782e711e0933f1d3ee40e2fe)

 app/tools/gimpselectionoptions.c |  2 ++
 app/tools/gimpselectionoptions.h |  1 +
 app/tools/gimpselectiontool.c    | 10 +++++++---
 3 files changed, 10 insertions(+), 3 deletions(-)
---
diff --git a/app/tools/gimpselectionoptions.c b/app/tools/gimpselectionoptions.c
index 1fb932e9a5..45993864a5 100644
--- a/app/tools/gimpselectionoptions.c
+++ b/app/tools/gimpselectionoptions.c
@@ -219,6 +219,8 @@ gimp_selection_options_gui (GimpToolOptions *tool_options)
     gtk_box_pack_start (GTK_BOX (vbox), hbox, FALSE, FALSE, 0);
     gtk_widget_show (hbox);
 
+    options->mode_box = hbox;
+
     label = gtk_label_new (_("Mode:"));
     gtk_box_pack_start (GTK_BOX (hbox), label, FALSE, FALSE, 0);
     gtk_widget_show (label);
diff --git a/app/tools/gimpselectionoptions.h b/app/tools/gimpselectionoptions.h
index db3958fd33..9a2107dd7d 100644
--- a/app/tools/gimpselectionoptions.h
+++ b/app/tools/gimpselectionoptions.h
@@ -43,6 +43,7 @@ struct _GimpSelectionOptions
   gdouble          feather_radius;
 
   /*  options gui  */
+  GtkWidget       *mode_box;
   GtkWidget       *antialias_toggle;
 };
 
diff --git a/app/tools/gimpselectiontool.c b/app/tools/gimpselectiontool.c
index 968df6d6f9..bf75d9769f 100644
--- a/app/tools/gimpselectiontool.c
+++ b/app/tools/gimpselectiontool.c
@@ -470,14 +470,16 @@ gimp_selection_tool_start_edit (GimpSelectionTool *sel_tool,
                                 GimpDisplay       *display,
                                 const GimpCoords  *coords)
 {
-  GimpTool *tool;
-  GError   *error = NULL;
+  GimpTool             *tool;
+  GimpSelectionOptions *options;
+  GError               *error = NULL;
 
   g_return_val_if_fail (GIMP_IS_SELECTION_TOOL (sel_tool), FALSE);
   g_return_val_if_fail (GIMP_IS_DISPLAY (display), FALSE);
   g_return_val_if_fail (coords != NULL, FALSE);
 
-  tool = GIMP_TOOL (sel_tool);
+  tool    = GIMP_TOOL (sel_tool);
+  options = GIMP_SELECTION_TOOL_GET_OPTIONS (sel_tool);
 
   g_return_val_if_fail (gimp_tool_control_is_active (tool->control) == FALSE,
                         FALSE);
@@ -486,6 +488,8 @@ gimp_selection_tool_start_edit (GimpSelectionTool *sel_tool,
     {
       gimp_tool_message_literal (tool, display, error->message);
 
+      gimp_widget_blink (options->mode_box);
+
       g_clear_error (&error);
 
       return TRUE;