First of all, it's absolutely great to have a new mIRC version! As many substantial things have been added/changed, of course it can be expected a number of new bugs have been introduced as well. This is, I believe, one of them.
In mIRC 6.16 and before, one would only be able to start marking text by initially clicking (+holding) the left mouse button on a part of the window that actually contained a text character under the mouse cursor. The new mIRC 6.17 changes this behaviour, by also letting the text marking start by clicking on areas of the text windows that do not contain text. The actual text marking then starts on the far right of the text on the left of this position. I assume that this was changed to make it easier to copy whole lines at once .
However, this feature currently does not work for at least:
- lines that contain any control code ;
- lines that are wrapped.
So much for the bug report - however, I'd like to add the following: due to this new feature (and despite the fact that it's not fully functional), I am now constantly losing the contents of my clipboard by accidentally selecting lines of text. This is due to the fact that among other things, I am used to
activating mIRC by clicking on unused text area, and simply clicking randomly on unused text areas as well. These are very, very old habits.
Therefore I would really, REALLY like to request that this feature be made optional, simply because I find it incompatible with the way I am using mIRC. I realize that I'm not putting up much of a defense here, I can only hope that many more people will agree with me at this point.
 And thus, that this is a feature at all. It is not mentioned explicitly in versions.txt
 This includes part/kick/quit/topic/etc messages, which contain a ^O character.