On 9 Aug 2016, at 11:24, Kim Ahlström wrote:

I noticed recently that the nightly builds started wrapping non-monospaced long before the line hits the soft wrap column or window frame.
[…]
After a little bit of sleuthing I think the relevant commit is https://github.com/textmate/textmate/commit/f487c5d57585f98d16273e0fa63b8a3d7c343df0

Thanks for the detailed report, the change from em-space to en-space was a mistake on my part and next build will revert to use the proper metric.