On 15 Nov 2018, at 2:19, Jacob Carlborg wrote:

Seems like the source list style for the file browser broke in the latest release, rc.19. Running macOS 10.13.

I assume you refer to https://github.com/textmate/textmate/commit/d27c779c60cde1089ac6cdb68b764174eaabb2a1

As alluded to in a previous post, it may end up in a sidebar split view item, which introduces the source list rendering again, but this is 10.11 and there are some rendering issues.