When I compose a message in an RTL language (Hebrew in my case), the arrow keys move the cursor to the opposite direction, i.e. Left arrow moves the cursor to the right, and right arrow moves the cursor to the left. The Backspace and Delete keys work fine.
Oh wow this is no good! Sorry for the hassle. It sounds like we’ve inherited this from this issue upstream: ianstormtaylor/slate#2963. Will see if we can contribute a patch back!
I can confirm this is still an issue on Mailspring 1.8.0 and Ubuntu 20.04. Slate is sitting on some PRs to fix this, and have incorrectly closed the bug.
This isn’t really anything we can act on, especially since the fixing PRs are stalled. We just have to wait.