[platform-dev] Help!! Why my activities doesn't work? It's so strange!

["su tonyws" <tonyjabber@xxxxxxxxx>]

I use activities in my rcp plugin.xml to filter out some actionsets as below:
   <extension point="org.eclipse.ui.activities">
      <activity name="Disable Set" 
                  id="filter"  description="a" />      
      <activityPatternBinding  activityId="filter"
             pattern="org\.eclipse\.ui\.ide/org\.eclipse\.ui\.WorkingSetActionSet" />
   </extension>

But this activities doesn't work!  The workingset button is still in the toolbar.

Then I changed the activityPatternBinding  to below, it works:
<activityPatternBinding  activityId="filter"
             pattern="org\.eclipse\.ui\.ide/.*" />


Anyone knows why the first one doesn't work??

Below is the actionsets definition in plugin.xml of org.eclipse.ui.ide:
    <actionSet label="..." description="..." visible="true" id="
org.eclipse.ui.WorkingSetActionSet">
      ...
  </actionSet>