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
* Return whether or not generator is the selected one.
	 * 
	 * @param generator
	 * @return boolean
	 */
	boolean isShowing(MarkerContentGenerator generator) {
		return this.builder.getGenerator().equals(generator);
	}
	/**
	 * Open the filters dialog for the receiver.
	 */
	void openFiltersDialog() {
		FiltersConfigurationDialog dialog = new FiltersConfigurationDialog(
				new SameShellProvider(getSite().getWorkbenchWindow().getShell()),
				builder);
		if (dialog.open() == Window.OK) {
			builder.updateFrom(dialog);
		}
	}
	/**
	 * Open the selected markers
	 */
	void openSelectedMarkers() {
		IMarker[] markers = getSelectedMarkers();
		for (int i = 0; i < markers.length; i++) {
			IMarker marker = markers[i];
			IWorkbenchPage page = getSite().getPage();
			openMarkerInEditor(marker, page);
		}
	}