Show/Hide Menubar and Dock Icon on macOS

[elsiehupp]

Branched from #2959.

This pull request adds code to make it so that the onboarding wizard and the settings dialogue both behave like foreground windows on macOS. When either window opens, the application spawns a dock icon and displays a menubar, and when the window is closed, the dock icon despawns, and the menubar is replaced with whatever other application is now in the foreground.

On Linux (or, at least GNOME), this behavior is automatically implemented when the Qt::Window flag is used. The behavior is especially important on macOS, because a Qt::Window can be maximized, but without a menubar, the application is unable to show the titlebar containing the “stoplight” buttons, so it is very difficult to un-maximize it. (The dock icon and menubar are a package deal in Cocoa, so you can’t have one without the other. While the dock icon isn’t as immediately necessary as the menubar on macOS, implementing a temporary dock icon on macOS has the added benefit of being consistent with the existing behavior on Linux.) The fact that the Qt::Window flag does not implement this behavior on macOS by default should probably be rightly considered a bug in Qt, but I digress.

I was unable to get a working copy of Windows installed on my computer, so I was unable to test whether the behavior of Qt::Window on Windows is more like Linux or more like macOS. The way the ForegroundBackground class I created is structured makes it easy to add a Windows implementation after the fact, and indeed my original intention was to include implementations for multiple different platforms in this pull request.

Ultimately, because the behavior did not require a custom implementation on Linux (or, at least GNOME), and because I was unable to set up a Windows development environment, I decided to make this pull request solely include the macOS implementation. I also haven’t been able to test the behavior on KDE or any other Linux shells aside from GNOME, but there aren’t any other open issues about the existing behavior of the application’s dock icon, so further shell-specific implementations can also safely wait.

It’s worth noting that the onboarding wizard already uses the Qt::Window flag, so the changes I’ve made here fix the existing issues of it being difficult to exit fullscreen and it being difficult to quit the application from this wizard. This pull request is a prerequisite for adding the Qt::Window flag to the settings dialogue, because it would have the same issues that already exist for the onboarding wizard.

There may be other places where it would be desirable for Nextcloud to temporarily spawn a dock icon and a menubar, but like the possible Windows and non-GNOME Linux implementations, I feel like they can be safely deferred to a later pull request.

[elsiehupp]

By the way, what is the 0. Needs triage label supposed to mean in this case? As far as I can tell, the numbered labels are a vestige of the GitHub Projects pseudo-agile workflow (which we aren’t really using), and 0. Needs triage is for Issues that have yet to be assigned to a project, so it doesn’t really make sense to apply to a pull request.

[elsiehupp]

I should also emphasize that the weird structure of ForegroundBackground, with multiple layers of interfaces, etc., is primarily necessary in order to get C++ and Cocoa/Objective-C to play nice together. The fact that it’s conducive to allowing additional platform-specific implementations is kind of just gravy.

[elsiehupp]

This is still ready for review…

[elsiehupp]

@nextcloud/desktop can someone please review this so it can get merged? And then review both #2959 and eventually #2974? #700 continues to be a significant pain for me on a day-to-day basis, and this pull plus #2959 fixes it.

[nextcloud-desktop-bot]

AppImage file: Nextcloud-PR-3014-9f91c62609bfa4028007d1ccd7f3db6d0d27c459-x86_64.AppImage

To test this change/fix you can simply download above AppImage file and test it.

Please make sure to quit your existing Nextcloud app and backup your data.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
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No Coverage information
0.0% Duplication

[elsiehupp]

I went ahead and (at @FlexW’s suggestion) drastically narrowed the number of open pull requests I have. If it would be helpful, I could fairly easily combine this one back into #2959.