Bug 275509 [Viewers] Tree/TableViewer with cell navigation is not accessible
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/SWTFocusCellManager.java
});
		viewer.getControl().addListener(SWT.FocusIn, listener);
	}
	/**
	 * @return the cell with the focus
	 *
	 */
	public ViewerCell getFocusCell() {
		return focusCell;
	}
	void setFocusCell(ViewerCell focusCell) {
		ViewerCell oldCell = this.focusCell;
		if( this.focusCell != null && ! this.focusCell.getItem().isDisposed() ) {
			this.focusCell.getItem().removeDisposeListener(itemDeletionListener);
		}
		this.focusCell = focusCell;
		if( this.focusCell != null && ! this.focusCell.getItem().isDisposed() ) {
			this.focusCell.getItem().addDisposeListener(itemDeletionListener);
		}
		if( focusCell != null ) {
			focusCell.scrollIntoView();	
		}
		
		this.cellHighlighter.focusCellChanged(focusCell,oldCell);
	}
	ColumnViewer getViewer() {
		return viewer;
	}
}