I see this on v18 too. (Win7x64)
I've got about 50 files open right now and my file tab sort order is set to Most Recently Viewed. This means that most of my file tabs are off the screen to the right - If I scroll to the right (but not all the way to the end) to find my file and then click on it to display it, the tab will move to the far left (as expected) but the file tab view itself will stay at the current spot. Which means that I have to scroll all the way left to get to the file tab to appear again. My current workaround is to hit the "back" button (navigate backward) which will take me to the previous file and update the tab view then quickly scroll left on the file tabs to bring the file tab back into view.
Hitting the down arrow to bring up the list of windows and then selecting the file I want will sometimes (but not always?) update the file tab view appropriately.
Where this really came up was when I was jumping around the code looking up definitions (right click on method, click on go to definition) and then I'd look up to the file tab to see what file I was in and... Hey! Where's the active file tab?!
Additionally, it'd be nice if double click on the left or right arrows on the file tab view would jump you to the left or the right of the window list. (or maybe right click/jump?)
