GroupBox: hide notification when box is collapsed

All child elements except the group box header should be hidden
when the group box is collapsed.

eclipse-scout-core/src/form/fields/groupbox/GroupBox.less

@@ -36,7 +36,9 @@
     #scout.menubar-background-color-inherit;
   }
 
-  &.collapsed > .menubar {
+  &.collapsed > .menubar,
+  &.collapsed > .notification,
+  &.collapsed > .group-box-body {
     display: none;
   }
 
@@ -187,10 +189,6 @@
     padding-right: 0;
   }
 
-  .collapsed > & {
-    display: none;
-  }
-
   /* position scrollbar as right as possible to prevent overlapping field parts. */
 
   & > .scrollbar {