i'm curious as to why you suggested $dllcall then
It was in reply to cgfiend, who said that even when you use a DLL you'll have to bear a mIRC freeze. This would be true if you were to use $dll(), but now $dllcall() allows you to run the DLL in a separate thread and let mIRC continue normally.
For example,
$dllcall(file.dll, [color:blue]mass_ren_done, MassRename, c:\folder\)[/color] would return immediately to the script, leaving the renaming process in the background. When it's done, mIRC will call the custom alias you specified, "mass_ren_done".
