I've seen some different behavior and I'm assuming the gutter has gotten some love lately.
Unfortunately I've just found a bug where the gutter will fill half the window, over the text, its non-fatal and only triggers on the HTML drawer being resized, so its probably pretty low priority, but its easily reproducible on my system.
It seems to me the text content must be longer than the page window, and it must be scrolled some.
Gist of the markdown used is here: https://gist.github.com/anonymous/d1b02248ac263b868f15
An Image here: http://i.imgur.com/YnLrVBq.png
And here's a video of the bug: http://screencast.com/t/ib7nlyVh
Im using Command + Option + Control + P to show and Command + Option + Control + H to hide the drawer.
If the app looses focus, the bug fixes itself when it gains it back.
Thanks guys. Keep up the good work!
-- Graham P Heath