Adjustment allowed on SalesTaxForm for classes extending TAX

As , we know we are extending TAX class in order to have our own customization in place and then we use the below peice of code to show the Calculated TAX :

yourExtendedClass = new yourExtendedClass (buffer);
    yourExtendedClass .calc(true,false);
    Tax::showTaxes(menuitemDisplayStr(TaxTmpWorkSalesOrder),yourExtendedClass .CustTax(),buffer);


So now when you open the form , you will notice that Tab Adjustment is not available :




So what we need to do is , we have to override the method :


/// <summary>
/// Returns a Boolean value that indicates whether the current transaction being calculated supports
/// sales tax adjustments.
/// </summary>
/// <returns>
/// true if the current transaction supports sales tax adjustment; otherwise, false.
/// </returns>
/// <remarks>
/// By default, the current transaction does not supports sales tax adjustments.
/// </remarks>
public boolean useSalesTaxAdjustments()
{
    return true;
}



this will make sure that we are having Adjustment tab on same form :