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
/**
	 * Turn off all filters in the builder.
	 */
	void disableAllFilters() {
		builder.disableAllFilters();
	}
	/**
	 * Return the builder for the receiver.
	 * 
	 * @return CachedMarkerBuilder
	 */
	CachedMarkerBuilder getBuilder() {
		return builder;
	}
	/**
	 * Get the categories to expand for the receiver.
	 * 
	 * @return Collection of MarkerCategory.
	 */
	private Collection getCategoriesToExpand() {
		if (categoriesToExpand == null) {
			categoriesToExpand = new HashSet();
			if (this.memento != null) {
				IMemento expanded = this.memento.getChild(TAG_EXPANDED);
				if (expanded != null) {
					IMemento[] mementoCategories = expanded
							.getChildren(TAG_CATEGORY);
					MarkerCategory[] markerCategories = builder.getCategories();
					if (markerCategories != null) {
						for (int i = 0; i < markerCategories.length; i++) {