Thanks for your bug report. I was able to reproduce this issue. It was due to the mIRC v7.42 Item 27 fix in versions.txt related to this post. I have found an alternative fix for item 27 that also resolves the current issue. However, the fix still involves a change to the focusing routine, which is somewhat tricky as even small changes can have side-effects. As this bug affects the interface and will be experienced by many users, I plan to release a new version soon.