private void updateSelection(boolean add) {
			if (add) {
				selection.addRange(anchorPoint, scrollPoint);
			}
			else {
				selection.removeRange(anchorPoint, scrollPoint);
			}
			selectionChanged = true;
		}
Checks if the "control" modifier is on and the "shift" modifier is not.
Ghidra/Framework/Docking/src/main/java/docking/widgets/fieldpanel/FieldPanel.java