Bug 208103 [Markers] Mark Completed needs a busy cursor
As it is moderately time consuming
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/views/markers/MarkerViewHandler.java
try {
			PlatformUI.getWorkbench().getOperationSupport()
					.getOperationHistory().execute(operation, monitor, uiInfo);
		} catch (ExecutionException e) {
			if (e.getCause() instanceof CoreException) {
				StatusManager.getManager().handle(
						StatusUtil
								.newStatus(IStatus.ERROR, title, e.getCause()),
						StatusManager.SHOW);
			} else {
				StatusManager.getManager().handle(
						StatusUtil.newStatus(IStatus.ERROR, title, e));
			}
		}
	}
	/**
	 * Get the selected markers for the receiver in the view from event. If the
	 * view cannot be found then return an empty array.
	 * 
	 * @param event
	 * @return {@link IMarker}[]
	 */
	public IMarker[] getSelectedMarkers(ExecutionEvent event) {
		MarkerSupportView view = getView(event);
		if (view == null)
			return EMPTY_MARKER_ARRAY;
		return view.getSelectedMarkers();
	}
}