Add RTL support to slack desktop.
It is only tested For version 3.3.3 on windows 10.
On Windows, Find your Slack's application directory: %homepath%\AppData\Local\slack\
Open up the most recent version (e.g. app-3.3.3) then open resources\app.asar.unpacked\src\static\ssb-interop.js (The address is something like: C:\Users\yourName\AppData\Local\slack\app-3.3.3\resources\app.asar.unpacked\src\static\ssb-interop.js)
Copy all the code from the "rtl.js" file and and add them to the very bottom of that file(ssb-interop.js), then restart slack.