>I don't think Thisform is available during property evaluation but if you put your code in an UDF and reference it instead, it may work.
I've had a case when it would run code in a procedure file if it was open, but would ignore it if it was not. It didn't use the result - the .caption="=someroutine('parameter')" would run (I know because it referenced a table which wasn't open so it would error out), but the caption property remained. IOW, I could have used this for some sideeffects - to, maybe, open some tables, procedure files, load builders and whatnot, and maybe even get a reference to the class via aSelObj(). Didn't try, though, my builders run from the command window, so I didn't need this and couldn't think of another use for it.