Bug 216811 [Markers] ExtendedMarkersView#setFocus doesn't
The result is that focus is lost if you drag the view to another stack... The most common implementation seems to be 'viewer.getControl().setFocus()... To test: select an element in the Problems or Tasks view. Drag the view to a new location (could be in an existing stack or a new one) notice that while the view is the active view the arrow keys don't navigate...
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/views/markers/ExtendedMarkersView.java
partListener = getPartListener();
		getSite().getPage().addPartListener(partListener);
		pageSelectionListener.selectionChanged(getSite().getPage()
				.getActivePart(), getSite().getPage().getSelection());
		viewer.addOpenListener(new IOpenListener() {
			public void open(OpenEvent event) {
				openSelectedMarkers();
			}
		});
		viewer.getTree().addTreeListener(new TreeAdapter() {
			/*
			 * (non-Javadoc)
			 * 
			 * @see org.eclipse.swt.events.TreeAdapter#treeCollapsed(org.eclipse.swt.events.TreeEvent)
			 */
			public void treeCollapsed(TreeEvent e) {
				removeExpandedCategory((MarkerCategory) e.item.getData());
			}
			/*
			 * (non-Javadoc)
			 * 
			 * @see org.eclipse.swt.events.TreeAdapter#treeExpanded(org.eclipse.swt.events.TreeEvent)
			 */
			public void treeExpanded(TreeEvent e) {
				addExpandedCategory((MarkerCategory) e.item.getData());
			}
		});
		
		viewer.getControl().addHelpListener(new HelpListener() {
			/*