Bug 114492 [WorkingSets] working sets: edit dialog should not display an error on open
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/workingsets/JavaWorkingSetPage.java
setPageComplete(errorMessage == null);
	}
	
	private boolean hasCheckedElement() {
		TreeItem[] items= fTree.getTree().getItems();
		for (int i= 0; i < items.length; i++) {
			if (items[i].getChecked())
				return true;
		}
		return false;
	}
	
	private void findCheckedElements(List checkedResources, Object parent) {
		Object[] children= fTreeContentProvider.getChildren(parent);
		for (int i= 0; i < children.length; i++) {
			if (fTree.getGrayed(children[i]))
				findCheckedElements(checkedResources, children[i]);
			else if (fTree.getChecked(children[i]))
				checkedResources.add(children[i]);
		}
	}
	void handleCheckStateChange(final CheckStateChangedEvent event) {
		BusyIndicator.showWhile(getShell().getDisplay(), new Runnable() {
			public void run() {
				IAdaptable element= (IAdaptable)event.getElement();
				boolean state= event.getChecked();		
				fTree.setGrayed(element, false);
				if (isExpandable(element))
					setSubtreeChecked(element, state, state);