I have found when I'm entering posts with large images or tables, that the editor area is just too small, and it's hard to arrange everything.

Now, with the new Fullscreen mode, you can expand the editor to fill the whole screen, editor you post, and then switch back to "regular" mode to post it.

All your have to do is to click the new Toggle Fullscreen Mode toolbar button (in the top-left of the toolbar), and the screen toggles back & forth between normal mode and fullscreen mode.