reset previous selection provider when styled text is disposed

de.itemis.xtext.utils/plugins/de.itemis.xtext.utils.jface/src/de/itemis/xtext/utils/jface/viewers/StyledTextXtextAdapter.java

@@ -375,8 +375,12 @@ public class StyledTextXtextAdapter {
 		}
 
 		public void widgetDisposed(DisposeEvent e) {
-			((StyledText) e.getSource()).removeFocusListener(this);
-			((StyledText) e.getSource()).removeDisposeListener(this);
-		}
+            if (selectionProviderOnFocusLost != null) {
+                site.setSelectionProvider(selectionProviderOnFocusLost);
+            }
+            ((StyledText) e.getSource()).removeFocusListener(this);
+            ((StyledText) e.getSource()).removeDisposeListener(this);
+        }
+
 	}
 }