@Override
	public Rectangle getCursorBounds(int row, int col) {
		if (row != 0) {
			return null;
		}
		int x = startX + metrics.stringWidth(text.substring(0, col));
		return new Rectangle(x, -heightAbove, 2, heightAbove + heightBelow);
	}
@see docking.widgets.fieldpanel.field.Field#isValid(int, int)
Ghidra/Framework/Docking/src/main/java/docking/widgets/fieldpanel/field/SimpleTextField.java