Anonymous

      <handler
            class="org.eclipse.team.internal.ccvs.ui.actions.CheckoutWizardAction"
            commandId="org.eclipse.team.cvs.ui.checkout">
                           <visibleWhen
                     checkEnabled="false">
                  <with
                        variable="selection">
                     <test
                           property="z.ex.propertyTester.selection.count"
                           value="1">
                     </test>
                  </with>
               </visibleWhen> 
</handler>