One thing i am having a hard time dealing with is action items are on the opposite end of the screen. If i select one or multiple items, all action items are way on the lower right side of the screen. I am constantly having to move my mouse from one end of the screen to the other. With RB6, all the action items are on top. So it is never far away from the check boxes or the message preview or message popup. I never have to move my mouse constantly from one end of the screen to the other.
The same thing with the HTML dialogue. I click allow HTML and the check box to click to accept it is on the far right. As there is no way to always allow HTML I find myself constantly moving my mouse from one end of the screen to the other.
Perhaps those things sound petty, but to me it is a real turn off. I figured i could get used to it given time, but unfortunately i am not getting used to it. I am still using RB6 more than the RB7 due to little things like that. I have also started to use https://www.protonmail.com for some things and i really enjoy their interface and how things work.