When the major version 7 came out I expected some UI changes. But there were no major changes in the design or rather no changes. I would like to suggest a few UI related upgraded. A more responsive windows. The items of the columns could be made compact like the mail list menu , Postbox client is running. They have done quite a good job with the UI while maintaining the classic look. Those who opt for all columns are going to have to do lot of horizontal scrolling. More modern looking icons which looks good in high DPI screens would be better. A side bar with two windows .. one listing the email accounts and other displaying the folders of the account. The new client in scene , Nylas N1 has done a good job. I am referring to third party clients to give a better understanding in what I mean. These UI changes can increase the productivity of The Bat! to great extend. While you are focused to extend the fuctionality and core of the great client, please try to give some time to the UI too.. And then no other client can stand up to The Bat!  .. Long live The Bat!