Improved, but still a couple of problems.

This app has much improved over the past year or so. I previously had a number of issues, but these have mostly been fixed, with the exception of the following one:

I do a lot of typing in Japanese, and due to the method used in typing Japanese, we often have to use the escape key. This forces the window to disappear.

The only other issue is that the spell check is not automatic. Ive forgotten to do it on more than one occasion, and cursed myself afterwards when I see spelling errors in my mails. Ive tried to find a setting to make the spellcheck automatic, but if one exists, its not in an intuitive location.

Mountfujay about MailTab Pro for Gmail - Email Client, v5.6