Why doesn't someone just write a Dialog Maker program in mIRC script?
Someone did once, and the thing was very buggy! The script utilized mIRC's picture window support, and it was very inaccurate when it came to trying out the dialog's source code that you created. If I were you, I wouldn't even waste my time attempting to script an mIRC dialog maker.
Khaled should design an external program to design mIRC dialogs. Now that would be worth downloading! Yeah, I know, mIRC is not an operating system... *Sigh*

One more thing, is there anyone out there who actually designs their dialogs "the good ol' fashioned way", without the use of a program?