Port to GTK4

[leolost2605]

Fixes #655

This should work now.

Todo:

• window drag doesn't work on X11 (i'd like to treat this as not blocking because I'm not quite sure what's going on here and kinda consider X11 only legacy anyways but idk)
• The transparency doesn't fully work (probably a CSS issue idk)

Misc:

• We get a warning about gtk_is_ancestor receiving null everytime an indicator is opened but idk why and wouldn't consider it blocking i guess?

[danirabbit]

I think probably the best way forward for development is I can create a new packaging branch based on this branch and then build that in daily so we can start building indicators against it etc

But I'm not sure what trying to upgrade this mid-cycle looks like, so I'd like to leave it unmerged for now until we have a plan around how to handle the packaging/upgrade.

[danirabbit]

Don't forget to update deps on README and .github :)

[danirabbit]

There's a packaging branch now: https://github.com/elementary/wingpanel/tree/deb-packaging-gtk4

So we should have access to the library on OS 8 daily no problem to work with porting the other indicators when this builds: https://code.launchpad.net/~elementary-os/+recipe/wingpanel-8-daily

You might want to temporarily change the meson project name here to io.elementary.wingpanel-8 or something so that you can install them both at the same time for testing? Otherwise the io.elementary.wingpanel-8 package will refuse to install because of the file conflicts. But this package name will eventually be reverted anyways so that's optional I guess 🤷‍♀️

[danirabbit]

Looks like we didn't properly update the library stuff so we could at least try to build indicators:

 trying to overwrite '/usr/include/wingpanel/wingpanel.h', which is also in package libwingpanel-dev 8.0.3+r719+pkg73~daily~ubu
ntu8.1

[leolost2605]

Looks like we didn't properly update the library stuff so we could at least try to build indicators:
trying to overwrite '/usr/include/wingpanel/wingpanel.h', which is also in package libwingpanel-dev 8.0.3+r719+pkg73dailyubu
ntu8.1

@danirabbit I did something in #605 lmk if that's right :)

[danirabbit]

Finally starting to test this! It looks like we've got some issues with

• Indicators losing focus
• The panel not being transparent when it should be. Changing the wallpaper sets it correctly but then if you switch workspaces for example it'll go back to being opaque
• Clicking inside an indicator closes that indicator and clicks on buttons etc aren't accepted

[danirabbit]

Interestingly, I can't reproduce the issue with indicators closing without accepting clicks on my Starlite running at 1.5x scaling. So I wonder if it has to do with scaling somehow?

[danirabbit]

@leolost2605 can you resolve merge conflicts here?

Since we're dropping X11 in OS 9, I'm not worried about any X11 bugs here. We could drop X11 in master before merging this if it makes it easier. Or we could drop it in a commit after merging this. Happy either way!