Select a resource in the left menu tree. Right click on it. Now slowly move the cursor away and e.g. click on the open/close triangles for subcategories.
Sometimes the menu just stays on the screen hiding the resources behind it - see screen shot
This bug was previously known as http://jira.rhq-project.org/browse/RHQ-1972
Imported an attachment (id=368715)
this is the old jsf ui - we have gwt now