fix suggested button appearance

Content/UniversalEditor.Content.PlatformIndependent/Dialogs/DocumentPropertiesDialog.glade

@@ -24,6 +24,9 @@
                 <property name="can_focus">True</property>
                 <property name="receives_default">True</property>
                 <property name="use_stock">True</property>
+                <style>
+                  <class name="suggested-action"/>
+                </style>
               </object>
               <packing>
                 <property name="expand">True</property>

Libraries/UniversalEditor.UserInterface/Dialogs/CustomOptionsDialog.cs

@@ -41,6 +41,7 @@ namespace UniversalEditor.UserInterface.Dialogs
 			Buttons.Add(new Button(StockType.Cancel));
 
 			// Buttons[0].ResponseValue = (int)DialogResult.OK;
+			DefaultButton = Buttons[0];
 			Buttons[1].ResponseValue = (int)DialogResult.Cancel;
 		}