I couldn't find any threads on this or any information in the help file, but sorry if it's been stated before. When I copy text from a channel window you can only copy the amount of lines you can see. By this I mean there could be 300 lines in the window but obviously you aren't going to be able see all 300 lines.
Basically my suggestion is that I'd like to be able to copy all the text, or the amount of text that is highlighted when I release my mouse.
My main reason for this is people send me code to look at and since I can't copy all the code, I forget which line I'm to resume copying from, I find it rather annoying.