@Override
	public int getCharacterIndexForDataLocation(int dataRow, int dataColumn) {
		if (dataRow == row && (dataColumn >= column) && (dataColumn <= column + length())) {
			return dataColumn - column;
		}

		return -1;
	}
the offset within the field's row where this element begins
Ghidra/Framework/Docking/src/main/java/docking/widgets/fieldpanel/field/AbstractTextFieldElement.java