@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;
					}

					for (TreePath path : selectionPaths) {
						GTreeNode node = (GTreeNode) path.getLastPathComponent();
						if (node instanceof OutgoingCallsRootNode ||
							node instanceof IncomingCallsRootNode) {
							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