Bug 157174 [Viewers] Refactor new Viewer API
We are yet not completely happy with the API and refactor it.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ToolTipSupport.java
private static final int DEFAULT_SHIFT_Y = 0;
	
	ToolTipSupport(ColumnViewer viewer) {
		this.viewer = viewer;
	}
	
	/**
	 * activate tooltip support for this viewer
	 */
	public void activate() {
		deactivate();
		viewer.getControl().addListener(SWT.Dispose, listener);
		viewer.getControl().addListener(SWT.MouseHover, listener);
		viewer.getControl().addListener(SWT.MouseMove, listener);
		viewer.getControl().addListener(SWT.MouseExit, listener);
		viewer.getControl().addListener(SWT.MouseDown, listener);
	}
	
	/**
	 * deactivate tooltip support for this viewer
	 */
	public void deactivate() {
		viewer.getControl().removeListener(SWT.Dispose, listener);
		viewer.getControl().removeListener(SWT.MouseHover, listener);
		viewer.getControl().removeListener(SWT.MouseMove, listener);
		viewer.getControl().removeListener(SWT.MouseExit, listener);
		viewer.getControl().removeListener(SWT.MouseDown, listener);
	}
	
	private class MouseListener implements Listener {