[keybinding] Align 'Open Preferences' and 'Save As' keybindings with VS Code on Mac OS

[jankeromnes]

Fixes #6606.

What it does

In VS Code, the default keybinding to open Settings is:

• Cmd + , on Mac OS, and
• Ctrl + , on Linux and Windows

In Theia, it is currently Ctrl + , everywhere. While this works everywhere, it's perceived as surprising on Mac OS.

Thus, on Mac OS we want the default keybinding to be Cmd + ,. However:

• The previous keybinding should still work, in order to avoid nasty surprises for users who got used to it
• While the new keybinding works in Electron and in browser/Chrome, it doesn't work in browser/Firefox. So on Firefox Mac, the default keybinding should remain Ctrl + ,

How to test

• In Electron and in Chrome:
  • both Ctrl + , and Ctrl + , should open the Preferences
  • the menu entry File > Settings > Open Preferences should show ⌘, as the default keybinding
• In Firefox:
  • only Ctrl + , can open the Preferences
  • thus the menu entry should still show ^, as the default keybinding
• On Linux and Windows:
  • the default keybinding should remain Ctrl + , everywhere (like VS Code)

Review checklist

• as an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• as a reviewer, I agree to behave in accordance with the review guidelines

[jankeromnes]

Signed off and added CHANGELOG.md entry.

[svenefftinge]

LGTM

[jankeromnes]

Thanks a lot @svenefftinge! I also threw in Save As, because it was a really small change (ctrl+shift+s to ctrlcmd+shift+s, works well in Electron + Firefox + Chrome).

[jankeromnes]

All green!

@svenefftinge or @akosyakov, please merge this PR for me, as I'm not yet a committer.

[akosyakov]

Should not be else here?

[jankeromnes]

This is intended: E.g. on Mac OS, in Chrome or Electron, we'll register both cmd+, and ctrl+,:

• cmd+, is the new default keybinding, while
• ctrl+, is there for people who already got used to typing ctrl+, for Preferences on Mac OS

Side note: In the File > Settings > Open Preferences menu entry, only the first keybinding shows up. (I double-checked that both keybindings work as expected, but that only the first is shown in the menu.)

[akosyakov]

ok

[kittaakos]

FYI: this change will disable the default Chrome binding for opening Chrome preferences on macOS. Was it on purpose?

[jankeromnes]

Yes, in order to follow VS Code's convention, we'd like to replace the behavior of cmd+, in browsers. (This only works in Chrome though -- Firefox will continue to open browser preferences, which is why we set a different default keybinding there).

Would you be surprised that hitting cmd+, in Theia in Chrome now opens the Theia preferences and no longer the Chrome preferences?

[kittaakos]

I thought we follow VS Code's convention in electron only and not disable/override the browser bindings.

[jankeromnes]

Good point. My understanding was that we try to follow VS Code's convention everywhere, but that in some browsers, it's sometimes impossible to override browser bindings (e.g. it's impossible to override cmd+, in Firefox) in which case we fall back on alternative bindings, but I may be wrong.

[kittaakos]

we try to follow VS Code's convention everywhere

I thought, no. My understanding was the following; we mimic the VS Code keymap in electron and leave the rest as is. For instance, why would we ever distinguish between macOS and other platforms when using Gitpod in Chrome.

CC: @svenefftinge

[svenefftinge]

Keybindings are part of a user's muscle memory. So we want to meet expectations as much as possible. I.e. the only reason to diverge from the default keybindings from VS Code (resp. keymaps like emacs or vim) is that browsers hinder us from handling certain keybindings.
Since CMD+, works in Chrome it should be used.