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
/*
			 * (non-Javadoc)
			 * 
			 * @see org.eclipse.jface.viewers.ITreeContentProvider#getChildren(java.lang.Object)
			 */
			public Object[] getChildren(Object parentElement) {
				MarkerItem[] children = ((MarkerItem) parentElement)
						.getChildren();
				return getLimitedChildren(children);
			}
			/**
			 * Get the children limited by the marker limits.
			 * 
			 * @param children
			 * @return Object[]