toggle the menubar with single Alt key press

[ronso0]

I decided to make another attempt to hide the menubar, this time by filtering a single Alt keypress + the essentials from #3184, but without the ControlObject and the skin button.
This is not available on macOS since there's a permanent global menu, also in fullcreen mode

I decided to require a single Alt press so Alt bindings in custom keyboard mappings don't toggle the menubar.

TODO

• single-press Alt to show or hide the menubar (press duration doesn't matter, only that there's no other key pressed between Alt press and release)
• hide the menu when going fullscreen ¹
• unhide the menubar if a menu hotkey (like Alt+F) is pressed while the menu is hidden ²
• add a label / dummy action to View menu "Toggle menu bar with Alt key"
  that action is not clickable (or does nothing respectively), so users have to press Alt themselves
• show a hint when going fullscreen
  
  I wonder if that should be omitted on macOS altogether?
• style hint for all skins
• test
• test
• test

TESTING (only done on *ubuntu so far)
I added debug output for the keystroke filtering, so in case something is not working as expected please run from the command line with --developer and share the relevant output snippets so we can debug it.

Closed #8902

Footnotes

1. for me this didn't work when I used the fullscreen hotkey (at least in debug builds I tested so far) because the window manager (xfwm4) hotkey and the Mixxx hotkey were identical, and the keystroke was consumed by the window manager.
   I have a workaround 167c569, though that's not applicable to linux distros with a global menu that require the current menubar hack, but for those hiding the menubar isn't available anyway 🤷 Maybe if my workaround is considered mergable I'll try to polish it so it replaces the hook to slotViewFullScreen on demand. ↩

2. I tested with Ubuntu Studio 20.04 (xfce desktop) (menus open immediately) and Ubuntu 22.04 (Gnome) (a second hotkey press is required to unroll the menu) ↩

[ronso0]

I tested with Ubuntu Studio 20.04 (xfce desktop) (menus open immediately) and Ubuntu 22.04 (Gnome) (a second hotkey press is required to unroll the menu) leftwards_arrow_with_hook

Somehow this broke after a recent update #11321
Fix is included in #11313 1a4d335

[ronso0]

unhide the menubar if a menu hotkey (like Alt+F) is pressed while the menu is hidden

Now this works flawlessly on both 20.04 with xfce and 22.04 with Unity.

[ronso0]

show a hint when going fullscreen

Automatically focusing the Okay button does not work on all platforms, yet.

[ronso0]

I've been using this + #11313 without and have any issues (Ubuntu 20.04 with vala global menu).
I'd appreciate if someone on Windows could give this a spin, before I find time to reactivate/fix my Win10 partition. @JoergAtGithub maybe?

edit macOS testing would be nice, too, but the changes don't shouldn't affect macOS at all.

[daschuer]

Works good here on Ubuntu Focal. The popup window can be improved for keyboard interactions.
I think it should be "Ok" instead of "Okay" like in other dialogs. You may also consider to enable Alt Shortcuts "Alt+o"

[JoergAtGithub]

I did a short test on Windows 11 and it works as expected!
My personal favorite would be to show a hamburger button for the menu as in #3189, but this is of cause beyond the scope of this PR.

[ronso0]

Great, thanks for testing!

The popup window can be improved for keyboard interactions.
I think it should be "Ok" instead of "Okay" like in other dialogs.

Yeah, I still have to polish the dialog.

You may also consider to enable Alt Shortcuts "Alt+o"

I don't understand... Alt+F is just an example, here all keys work and unhide the menu bar.

My personal favorite would be to show a hamburger button for the menu as in #3189, but this is of cause beyond the scope of this PR.

Yes, entirely.
Also, I intend to get this merged into 2.4, not 4.2 ; )

[daschuer]

You may also consider to enable Alt Shortcuts "Alt+o"

I don't understand... Alt+F is just an example, here all keys work and unhide the menu bar.

It is just that in case of a standard QMessageBox, the O if OK is underlined for pressing the button via Alt+O.

[ronso0]

(responding to @daschuer's review comment in #11313 )

I have just tested this a bit, with some results:

• The Menu bar disappears when going to fullscreen, which is OK, but it does not com back on window mode, which was my expectation. Maybe we should store the menu bar visible state for both independently. Default: Windowed = menu bar visible; Full-screen = menu bar hidden.

Users are notified how to toggle the menubar when going fullscreen, so they should know how to get it back in windowed mode. But indeed this is inconsistent with showing the menubar on each (windowed) start.
So yes, if someone always wants the menubar in windowed or fullscreen mode we could store the state.

Anyway, allowing to toggle the menubar is a significant change and we may make a step backwards and discuss the implementation options and how to let as many users as possible benefit from it.

1. We could also hide the menubar by default on each start and only show it on demand (state is not stored).
   This is actually my preferred solution, though it's not discoverable how to show the menubar. We may expect some users know this from Firefox / Thunderbird / SublimeText (actually I'm only aware of these Mozilla apps) / ... , but I suspect there'll be many support request "Where's the menubar???"
   So the question is how to make the toggle discoverable. A popup after upgrade would be okay for me (with the same 'Remind me again' checkbox).
2. Show it by default, show the Alt key hint when going fullscreen + the Alt hint in the View menu
   I think that way many users will miss it, e.g. if they are upgrading and are already somewhat used to the interface they won't dicscover the hint in the View menu. If they never use Mixxx in fullscreen mode (FullHD screens don't really require it) they'll also never see the popup. Then hiding the menubar will be like a hidden feature, even though many users may enjoy it.

• "Enter" is still not equal pressing Ok

So the Okay button is not focused when the hint pops up?
Should Enter close the dialog even if the checkbox has focus?

[ronso0]

The more I think about it I notice I prefer the way it's done in Firefox:

• menubar always hidden by default (fullscreen and window)
• press Alt to show the menubar and focus the first menu
• press menu hotkey to show the menubar and focus the requested menu
• hide menubar when it loses focus (menu action clicked || escape pressed || focused something else)

+

• show a popup after start to explain the new feature, incl. "Remind me again" checkbox

I'll test this in another branch so the different approaches can be tested easily.

[ronso0]

I'll close this one in favor of #11526
I messed something up (or rather wrong git rerere) during rebase onto main, and I prefer auto-hide anyway.