When using colors with /echo and /aline (and prolly any other command that allows you to specify a line color), using ^O won't keep the color setting when copying the colors. IMHO, mIRC should find some way of remembering line colors.
Example:
/echo 3 Some Text
With a ^O between Some and Text, it outputs:
Some Text
But copies as:
Some Text
A way mIRC can deal with this issue, would be to replace all the ^O's in a line with ^K(color) when a line color is specified. Then the line will copy correctly. If a line color is not specified, the ^O's should remain ^O's, so copying/reading on different colored backgrounds doesnt come out screwy.