Bug 275509 [Viewers] Tree/TableViewer with cell navigation is not accessible
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/SWTFocusCellManager.java
}
	abstract ViewerCell getInitialFocusCell();
	private void hookListener(ColumnViewer viewer) {
		Listener listener = new Listener() {
			public void handleEvent(Event event) {
				switch (event.type) {
				case SWT.MouseDown:
					handleMouseDown(event);
					break;
				case SWT.KeyDown:
					handleKeyDown(event);
					break;
				case SWT.Selection:
					handleSelection(event);
					break;
				case SWT.FocusIn:
					handleFocusIn(event);
					break;
				}
			}
		};
		viewer.getControl().addListener(SWT.MouseDown, listener);
		viewer.getControl().addListener(SWT.KeyDown, listener);
		viewer.getControl().addListener(SWT.Selection, listener);
		viewer.addSelectionChangedListener(new ISelectionChangedListener() {
			public void selectionChanged(SelectionChangedEvent event) {
				if( event.selection.isEmpty() ) {
					setFocusCell(null);
				}
			}