[gimp] app: properly grab focus when targetting text input of GimpSpinScale.

[Jehan <jehanp src gnome org>]

commit 3449652fe84b3e3167ada9808801031498c1bad6
Author: Jehan <jehan girinstud io>
Date:   Wed Nov 4 18:32:27 2020 +0100

    app: properly grab focus when targetting text input of GimpSpinScale.
    
    By just redirecting to parent signal handler, it was not properly
    grabbing focus. In particular for a text entry with number input, we
    want the text to be fully selected (because when we go for inputting
    numbers, it is more often than not because we want to enter free numbers
    very different from existing value).
    So let's grab the entry focus, hence fully select current number
    contents.

 app/widgets/gimpspinscale.c | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/app/widgets/gimpspinscale.c b/app/widgets/gimpspinscale.c
index f3293803b3..624df43f79 100644
--- a/app/widgets/gimpspinscale.c
+++ b/app/widgets/gimpspinscale.c
@@ -818,6 +818,10 @@ gimp_spin_scale_button_press (GtkWidget      *widget,
 
       return TRUE;
 
+    case TARGET_NUMBER:
+      gtk_widget_grab_focus (widget);
+      return TRUE;
+
     default:
       break;
     }