SessionManager.INSTANCE.addSessionsListener(new SessionListener());

public class SessionListener extends SessionManagerListener.Stub {
    @Override
    public void notify(Session notifiedSession, int notification) {
        if ((SessionListener.OPENED== notification){
ResourceSetListenerChangeListener resourceSetListenerChangeListener = new ResourceSetListenerChangeListener();
        session.getTransactionalEditingDomain().addResourceSetListener(resourceSetListererChangeListener);


    }
}

 private final class ResourceSetListenerChangeListener extends ResourceSetListenerImpl {

        @Override
        public void resourceSetChanged(ResourceSetChangeEvent event) {
                boolean myTargetLayerActivated = isActivated(event);
MyPluginActivator.getSessionToListenerMap().put(session,myTargetLayerActivated );
        
/**You also need to trigger the refresh of the tabbar to update the visibility manually by using org.eclipse.sirius.diagram.ui.tools.api.editor.DDiagramEditor.getTabBarManager().update(true)
from the current opened diagram editor**/ 

((DDiagramEditor)PlatformUI.getWorkbench().getActiveWorkbenchWindow().getActivePage().getActiveEditor()).getTabBarManager().update(true);

}
        @Override
        public boolean isPostcommitOnly() {
            return true;
        }

        @Override
        public NotificationFilter getFilter() {
            return NotificationFilter.NOT_TOUCH;
        }
    }

<visibleWhen checkEnabled="false">
      <with variable="activeEditor">
             <test property="testLayerActivatedForEditorSession"/>
         </with>
   </visibleWhen>

public class TestLayerActivatedForEditorSessionextends PropertyTester {
    public boolean test(Object receiver, String property, Object[] args, Object expectedValue) {
        if (receiver instanceof DDiagramEditor) {
return MyPluginActivator.getSessionToListenerMap().get(((DDiagramEditor)receiver).getSession());
     }
return false;
}