fix #900,dont hide panel in editMode

--when the context menu is destroyed it frees
the visibility blocker for hiding. This is true
in normal state but in editing mode it shouldnt
happen.

app/dock/dockmenumanager.cpp

@@ -61,7 +61,11 @@ void DockMenuManager::menuAboutToHide()
     }
 
     m_contextMenu = 0;
+
+    if (!m_dockView->containment()->isUserConfiguring()) {
         m_dockView->visibility()->setBlockHiding(false);
+    }
+
     emit contextMenuChanged();
 }