There are 2 bugs that I have noticed:
1. When having an active dcc session open and opening another one with the same nick, it will send text in the 2nd one to the 1st one
2. When trying to copy text from a window with text highlighted in the editbox also, it copies the text thats in the editbox. It would be good to copy the text thats highlighted in the window
Also, I am running the latest version mIRC v6.12