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
/**
	 * Register the context menu for the receiver so that commands may be added
	 * to it.
	 */
	private void registerContextMenu() {
		MenuManager contextMenu = new MenuManager();
		contextMenu.setRemoveAllWhenShown(true);
		getSite().registerContextMenu(contextMenu, viewer);
		
		if (!getSite().getId().equals(MarkerSupportRegistry.MARKERS_ID))
			getSite().registerContextMenu(MarkerSupportRegistry.MARKERS_ID,
					contextMenu, viewer);
		Control control = viewer.getControl();
		Menu menu = contextMenu.createContextMenu(control);
		control.setMenu(menu);
	}
	/**
	 * Remove the category from the list of expanded ones.
	 * 
	 * @param category
	 */
	void removeExpandedCategory(MarkerCategory category) {
		getCategoriesToExpand().remove(category.getName());
	}
	/**
	 * Preserve the selection for re-selection after the next update.
	 * 
	 * @param selection
	 */
	void saveSelection(ISelection selection) {