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
*/
			private TreeViewer getViewer() {
				return viewer;
			}
			/*
			 * (non-Javadoc)
			 * 
			 * @see org.eclipse.ui.progress.UIJob#runInUIThread(org.eclipse.core.runtime.IProgressMonitor)
			 */
			public IStatus runInUIThread(IProgressMonitor monitor) {
				if (viewer.getControl().isDisposed()) {
					return Status.CANCEL_STATUS;
				}
				if (monitor.isCanceled())
					return Status.CANCEL_STATUS;
				
				
				if (builder.isShowingHierarchy()
						&& getCategoriesToExpand().isEmpty()) {
					MarkerCategory[] categories = builder.getCategories();
					if (categories != null && categories.length == 1)
						getCategoriesToExpand().add(categories[0].getName());
				}
				getViewer().refresh(true);
				updateTitle();
				if (preservedSelection.size() > 0) {
					Collection newSelection = new ArrayList();
					MarkerItem[] markerEntries = builder.getMarkerEntries();
					for (int i = 0; i < markerEntries.length; i++) {
						Iterator preserved = preservedSelection.iterator();