Store wingpanel height in settings schema

[vjr]

Addresses elementary/gala#2560

Blocks elementary/gala#2924 to fix the issue.

[danirabbit]

gsettings should not be used as IPC. There's dbus for that

[vjr]

gsettings should not be used as IPC. There's dbus for that

Not even for a single property/integer? See https://github.com/elementary/wingpanel/blob/main/src/Services/BackgroundManager.vala#L70 isn't this doing just that? Although, I'll switch to using DBus. Thanks.

[danirabbit]

@vjr that's actually a setting from GTK settings so it's safe to use.

Glib.Settings are usually not safe to use because it will crash if keys are missing so you create a hard packaging dependency. And then we run into the issues of circular dependency. If the panel depends on Gala and Gala depends on the panel we get into a pickle. We need dependencies to go one way. So the rule of thumb is we shouldn't use other packages gsettings for settings if we can help it, and never for IPC