Using constants for position values

I can’t get this to work -

In a window I create a constant (say kTextFieldDefaultWidth as a number with a value of 100)
Select a textfield control and enter #kTextFieldDefaultWidth in the “width” field
The IDE decides I meant to enter 0 and adjusts the width of the control accordingly.

The constant trick appears to work for the position values of the window itself, but not for controls in it.
That’s Xojo 2016r4.1. Isn’t that supposed to work or am I doing something wrong?

Best, Max

for me the #k trick works only for some window properties like caption, headers,
if it does not work for a field you need, then fill a feature request ?
but yes I already noticed this does not work for all properties.