A few more bugs. If you have some better way for us to present these to you, please let us know. I'm not sure if commenting in this thread is better, or creating a new thread. If you prefer one over the other, again, let us know.
window.get_view_index() returns (-1, -1) for an untitled view. Probably related, using window.focus_view() on a view that doesn't exist on disk does not work.
Went to test the first bug I posted here (regarding a display error in the side bar) and got the following.
1. Start ST3
2. Open a folder.
3. Create a multi column view (I used 2)
4. Ensure side bar is visible and open files are not being shown.
5. Select a file for previewing (Must not be in the right most column).
6. Enable "Show Open Files"