Bug 213166 [Viewers] Problems with OwnerDrawLabelProvider.setUpOwnerDraw
3.4 M4 To set up the owner draw callbacks for a viewer OwnerDrawLabelProvider.setUpOwnerDraw is offered. The problem of this is: a. there's no way to uninstall the callbacks. In our views we want to allow to enable and disable owner draw in the preferences b. from an API client perspective, it would be nicer if the label provider could install itself when installed. A good solution would be to add more life cycle to a label provider. CellLabelProvider.initialize(ColumnViewer, int column) There's already ILableProvider.dispose when a label provider is removed from a viewer.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ColumnViewer.java
* @param busy
	 *            the new value of the busy flag
	 * 
	 * @since 3.4
	 */
	protected void setBusy(boolean busy) {
		this.busy = busy;
	}
	/**
	 * Returns <code>true</code> if this viewer is currently busy processing a
	 * refresh, add, remove, insert, replace, setItemCount, expandToLevel,
	 * update, setExpandedElements, or similar method that may make calls to
	 * client code. Column viewers are not designed to handle reentrant calls
	 * while they are busy. It is recommended that clients avoid using this
	 * method if they can ensure by other means that they will not make
	 * reentrant calls to methods like the ones listed above. See bug 184991
	 * for background discussion.
	 * 
	 * <p>
	 * This method is not intended to be overridden by subclasses.
	 * </p>
	 * 
	 * @return Returns whether this viewer is busy.
	 * 
	 * @since 3.4
	 */
	public boolean isBusy() {
		return busy;
	}
}