Bug 297731 [Filters] We could have IResourceFilterDescription#delete instead of IContainer#removeFilter ?
This is the pattern used for resource markers. It is just a minor issue, however would make new API look more consistent.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/dialogs/ResourceFilterGroup.java
FilterCopy filter = (FilterCopy) ((IStructuredSelection) selection)
						.getFirstElement();
				if (filter.getChildrenLimit() > 0) {
					FilterCopy newFilter = new FilterCopy();
					newFilter.setParent(filter);
					FilterEditDialog dialog = new FilterEditDialog(shell,
							newFilter);
					if (dialog.open() == Window.OK) {
						filter.addChild(newFilter);
						filterView.refresh();
					}
				}
			}
		}
		/*
		 * (non-Javadoc)
		 * 
		 * @see org.eclipse.jface.action.Action#isEnabled()
		 */
		public boolean isEnabled() {
			ISelection selection = filterView.getSelection();
			if (selection instanceof IStructuredSelection) {
				FilterCopy filter = (FilterCopy) ((IStructuredSelection) selection)
						.getFirstElement();
				return filter.getChildrenLimit() > 0;
			}
			return false;
		}
	}
	class FilterCopyDrop extends ViewerDropAdapter {