Well my scripts window navigation is broken now too.
I have a small status and channel windows dialog with a Hide All button. Until the previous mIRC version, this hided all windows initiated by the script. Now it suddenly filled the whole mIRC client area with titlebars similar to those from minimized windows.
And from that point, I can't make both window and minimized titlebar disappear anymore.
Do /window -h @bla -> there isnt any indication that newly created window is present, you have to go to the Window menu to make it appear (how it was and should be)
Now, do another /window -h @bla -> it minimizes so that titlebar below appears, instead of just hide (only visible in Window menu)