@Override
			public boolean isAddToPopup(ActionContext context) {
				Object contextObject = context.getContextObject();
				if (!(contextObject instanceof GTree)) {
					return false;
				}

				GTree gTree = (GTree) contextObject;
				TreePath[] selectionPaths = gTree.getSelectionPaths();
				if (selectionPaths.length == 0) {
					return false;
				}
				return true;
			}
A variable used to restrict open-ended operations, like expanding all nodes or filtering.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/calltree/CallTreeProvider.java