a GdkDisplay
a GtkStyleProvider
the priority of the style provider. The lower it is, the earlier it will be used in the style construction. Typically this will be in the range between %GTK_STYLE_PROVIDER_PRIORITY_FALLBACK and %GTK_STYLE_PROVIDER_PRIORITY_USER
Adds a global style provider to @display, which will be used in style construction for all GtkStyleContexts under @display.
GTK uses this to make styling information from GtkSettings available.
Note: If both priorities are the same, A GtkStyleProvider added through [method@Gtk.StyleContext.add_provider] takes precedence over another added through this function.