Bug 306231 The Regular Expression Resource Filter must gracefully handle invalid patterns
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/dialogs/ResourceFilterGroup.java
protected FilterCopyDrop(Viewer viewer) {
			super(viewer);
		}
		/*
		 * (non-Javadoc)
		 * 
		 * @see
		 * org.eclipse.jface.viewers.ViewerDropAdapter#performDrop(java.lang
		 * .Object)
		 */
		public boolean performDrop(Object data) {
			Object target = getCurrentTarget();
			if (target == null)
				target = filters;
			FilterCopy[] toDrop = (FilterCopy[]) data;
			if (target instanceof FilterCopy) {
				for (int i = 0; i < toDrop.length; i++)
					if (toDrop[i].equals(target)
							|| ((FilterCopy) target).hasParent(toDrop[i]))