public void setAllowNegativeValues(boolean b) {
		BigInteger currentValue = getValue();
		allowsNegative = b;
		if (!allowsNegative) {
			if (currentValue != null && currentValue.signum() < 0) {
				currentValue = null;
			}
		}
		updateTextField(currentValue);
	}
Sets whether or not negative numbers are accepted.

@param b if true, negative numbers are allowed.
Ghidra/Framework/Docking/src/main/java/docking/widgets/textfield/IntegerTextField.java