There is not.
With mIRC scripting alone, you cannot modify a dialog's size and controls once it's opened, you need dcx to do that.
You could put what you're doing in your init $devent inside an alias and call the alias when you want to reinitialize the dialog, but that only means changing the control's text etc, you can't remove/add more control or change any size.
That's being said, what you're talking about with option 1-4 or 5-8 in the dropdown combo list, it's entirely doable.
