No, I said we simply forgot about the feature when reviewing the original contribution. I would've expected that this feature would be part of the original contribution, but it wasn't, and so the feature is currently missing :)

@pisv FYI

@JonasHelming Thank you for letting me know about the issue.

FWIW, when #13916 was merged, there was no support for editor associations in Theia.

It was added later on in #14139.

I'll take a look and try to fix it.

Is it just me, or support for custom editors looks completely broken on the current master? I mean ordinary custom editors, not just side-by-side diff ones... Can someone please check?

@tsmaeder

@pisv Could you opena separate issue and what do you have in the log when opening those editors?

@tsmaeder I've opened #15416. No errors in the logs. Really nothing.

Coming back to the issue with editor associations not taking effect for diff editors, it looks like the culprit is that EditorManager.canHandle currently always returns 100 in case of a diff-URI. A matching custom editor will by default have a higher priority (200), which causes a custom side-by-side editor to open instead of the text compare editor, regardless of editor associations.

I'll submit a PR once #15416 is fixed.

The PR #15422 is ready for review. (There are some tests failing, which don't seem to be related to the PR.)