one of the major problems with /list is on large networks it makes mIRC lock up until its done, sadly this is due to how mIRC is coded. There is also no command in the RFC (I dont think) to tell the server to halt sending data to furfill a previous /list request (I may be wrong but im almost positive theres not). This puts the client at a disadvantage the only way to stop the filling of that window with channels is to ignore lots of data flooding mIRC from the server which lags the client anyway...

So based on my expierence with mIRC theres no way this can happen since mIRC when flooded with data from the server jsut about can only do one thing at a time anyway i dont think there will be an option to ignore the incoming data (which would effectivly halt it in the list box) however im all for the popups in that i like that idea and maybe like a /list @window to list to woujdl be neat