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
* Get all of the filters for the receiver.
	 * 
	 * @return Collection of {@link MarkerFieldFilterGroup}
	 */
	Collection getAllFilters() {
		return builder.getAllFilters();
	}
	/**
	 * Return all of the markers in the receiver.
	 * 
	 * @return IMarker[]
	 */
	IMarker[] getAllMarkers() {
		MarkerItem[] elements = builder.getElements();
		Collection allMarkers = new ArrayList();
		for (int i = 0; i < elements.length; i++) {
			addMarkers(elements[i], allMarkers);
		}
		IMarker[] markers = new IMarker[allMarkers.size()];
		allMarkers.toArray(markers);
		return markers;
	}
	/**
	 * Return the group used for categorisation.
	 * 
	 * @return MarkerGroup
	 */
	MarkerGroup getCategoryGroup() {
		return builder.getCategoryGroup();
	}