Make sure that default keyboard works

[peterhil]

The default keyboard shortcut does not work in Firefox 88 on Linux. Change it to something that works on:

• Different operating systems (Command vs. Ctrl)
• Different Firefox and Chrome versions

These shortcuts might work:

• Ctrl-B on Mac (Chrome and Firefox)
• Ctrl-Alt-B on Linux & Windows (Chrome and Firefox)

Or just use Ctrl-B everywhere?

Other options:

• Cmd-Opt-S / Ctrl-Alt-S
• Cmd-Ctrl-B / Ctrl-Alt-B

Notes:

• Ctrl-Alt modifiers can’t be used (on Chrome at least) because they conflict with AltGr
• Alt and Alt-Shift will open menus on Linux and Windows

Investigation:

Chrome on Mac:

• Cmd-B: Current default
• Ctrl-Opt-S: Available
• Cmd-Opt-S: Let's set it, but does not work
• Cmd-Ctrl-D: Dictionary

Firefox on Mac:

• MacCtrl-B: Available (and current default, MacCtrl means Ctrl)
• Cmd-B: Bookmarks sidebar
• Cmd-Shift-B: Bookmarks bar

Firefox on Linux:

• Ctrl-Alt-D: Available
• Ctrl-Alt-B: Available
• Ctrl-E: Available
• Ctrl-B: Bookmarks sidebar
• Ctrl-Shift-B: Bookmarks bar
• Ctrl-Shift-S: Firefox screenshots
• Ctrl-Alt-S: Saka (is this default?)
• Alt-S: Opens menu Sivuhistoria