This works as it has always worked, for me.
How to copy text, with bold/underline/color codes:
1. Press and hold down the CTRL key (either side).
2. Position your mouse, press the left button and drag it over the text you wish to select.
3. Release the mouse button.
4. Release the CTRL key.
The only thing that has changed recently is this:
6.03 - You can now drag your mouse over text from Right to Left.
6.10 - Pressing CTRL+C now actually copies the text instead of just aborting the selection. This still isn't the standard method of copying text in mIRC, but was added for compatability with people used to pressing CTRL+C.
- Raccoon