I think you do not really understand the problem.
In the left picture (v6.35)
In the right picture (v7.0)
On both screens I used the classic windows theme (WinXP) and set black color for Selected Items. For the mIRC editbox I also have a black color. In v7.0 we don't see the text selection. As for me what we should see as a color of selection is a reversed background color - as in v6.35.
attached image:
http://www.devilbat.neostrada.pl/difference.png