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
final TreeColumn column = (TreeColumn) e.widget;
				final MarkerField field = (MarkerField) column
						.getData(MARKER_FIELD);
				setPrimarySortField(field, column);
			}
		};
	}
	/**
	 * Return the selection listener for the page selection change.
	 * 
	 * @return ISelectionListener
	 */
	private ISelectionListener getPageSelectionListener() {
		return new ISelectionListener() {
			/**
			 * Get an ITaskListResourceAdapter for use by the default/
			 * 
			 * @return ITaskListResourceAdapter
			 */
			private ITaskListResourceAdapter getDefaultTaskListAdapter() {
				return new ITaskListResourceAdapter() {
					/*
					 * (non-Javadoc)
					 * 
					 * @see org.eclipse.ui.views.tasklist.ITaskListResourceAdapter#getAffectedResource(org.eclipse.core.runtime.IAdaptable)
					 */
					public IResource getAffectedResource(IAdaptable adaptable) {
						Object resource = adaptable.getAdapter(IResource.class);
						if (resource == null)
							resource = adaptable.getAdapter(IFile.class);