One thing which is making RubyMine a chore to work with is the way it handles open tabs when opening new tabs. I've selected for it to close older unused tabs, but this isn't about closing tabs, it's about what tabs show on a single line list that leaks off the edge of the tab window.
For some reason, RubyMine will hide the last tab I was in when opening a new tab, and if my tab count reaches the limit, it will sometimes close that tab. So if I want to work in 2 tabs at the same time, I'm oftentimes having to open a new tab, then make sure the other tab is still there, and if not, open that again. I think a simple method whereby the new tab is prepended onto the tab list would work fine.