You're missing the point. MDI child windows still have titlebars unless you specify otherwise-- and because you did not specify otherwise, they also have a minimum size limitation. This is not mIRC's doing, this is how Windows works. If you want a smaller window, you'll have to remove the titlebar buttons as shown in my original post.
Is this not what you're seeing?:
(40x60 without +L)
(40x60 with +L)
Try to resize the first Window and you'll see that you simply *cannot* make it any smaller. This is proof that it is a Windows issue, not mIRC. mIRC is indeed trying to make the window 40x60 and it is Windows that is not letting it- there's really nothing mIRC can do in this case. You as the scripter need to remove the window border.
Hidden windows don't make a difference. Just because a window is hidden doesn't mean Windows does not allocate titlebar or borders to it. Hidden means not drawn on the screen, not "no borders or titlebar"-- a hidden window must still respect the boundary requirements of the window manager.
See /help /window and specify the correct border type (maybe you want +b?) so that you can make the window the correct size.
