Think you misunderstand what's going on here.
mIRC is a client for Windows and the latest news I have is that it's not on any other platform. Secondly, the DLL is based on the windows API and yes there are some controls that are related to the version of IE as it's the application that bundled the comctl32.dll file in the old versions of Windows. So some controls are dependant on the IE version (the comctl32.dll file) installed on their computers. On XP, having or not IE doesn't matter, but it does on older Windows versions.
Secondly, people want DLLs that are consistant with the system and usually small because they need to package it with their script or addons. Now building a [INSERT YOUR FAVORITE NON WINDOWS GUI AVAILABLE ON WINDOWS] would grow the DLL size so much that this requirement would vanish and I would probably need to package a whole lot of other DLLs to be loaded by the "mIRC DLL" that people would have to shove around to use it.
I don't have these constraints making a Windows API DLL as people that use mIRC are on windows and they already have the API DLLs right on their system available.
