[glade] GladeEditorProperty: Add 4px box spacing

[Tristan Van Berkom <tvb src gnome org>]

commit 82bc6865f0e90119c2c310f305d7092ebdbfb38d
Author: Tristan Van Berkom <tristan vanberkom codethink co uk>
Date:   Sat Oct 29 20:00:14 2016 +0900

    GladeEditorProperty: Add 4px box spacing
    
    This causes the optional properties with the added check mark to
    look much better.
    
    From patch contributed by Lukas K <lu 0x83 eu> on bug 351645

 gladeui/glade-editor-property.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/gladeui/glade-editor-property.c b/gladeui/glade-editor-property.c
index cc3eded..58cd27e 100644
--- a/gladeui/glade-editor-property.c
+++ b/gladeui/glade-editor-property.c
@@ -655,6 +655,7 @@ glade_editor_property_init (GladeEditorProperty *eprop)
 {
   eprop->priv = glade_editor_property_get_instance_private (eprop);
 
+  gtk_box_set_spacing (GTK_BOX (eprop), 4);
   gtk_orientable_set_orientation (GTK_ORIENTABLE (eprop),
                                  GTK_ORIENTATION_HORIZONTAL);
 }