Locking and unlocking the window is what I eventually ended up doing here is a snip it of my code.
Code:
OnPress="window_property unlock Custom RS_C2C
Parent.Parent.RS_C2C.Height=(COND ? 2 : 1) COND=(checked == true)
window_property lock Custom RS_C2C
Parent.CancelSpellCast.LocalText=COND"
That was some time ago though! Have you been on vacation? :P