void saveFilterRestoreState() {
		// this may be called by sub-filter tasks and we wish to save only the first one
		if (filterRestoreTreeState == null) {
			filterRestoreTreeState = new GTreeState(this);
		}
	}
Signal to the tree that it should record its expanded and selected state when a new filter is
applied
Ghidra/Framework/Docking/src/main/java/docking/widgets/tree/GTree.java