Fix toolbar render problems in dark mode on resizing #536

- Toolbar has in dark mode now a dedicated color
  instead of css inheritance. A parent container
  change by resizing does not change the toolbar color any longer
- The color is choosen in way that the main toolbar looks as expected
  before. Also the toggle border is now visible again, which could
  address #467 as well.

Signed-off-by: Albert Tregnaghi <albert.tregnaghi@gmail.com>

bundles/org.eclipse.ui.themes/css/dark/e4-dark_globalstyle.css

@@ -57,9 +57,9 @@ TabFolder > Composite > * > * { /* [style~='SWT.NO_BACKGROUND'] <- generate E4 n
 	color:'#org-eclipse-ui-workbench-DARK_FOREGROUND'; 
 }
 
-/* Toolbar should inherit the colors of its container to avoid drawing artifacts*/
 ToolBar {
-	background-color:inherit;	
+    /* Because resizing leads to a change in style inheritance we do not use 'inherit', but define an explicit background color here */
+    background-color: '#org-eclipse-ui-workbench-DARK_BACKGROUND';
 }
 
 Combo,