a #GdkScreen
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
3.0
Adds a global style provider to @screen, which will be used in style construction for all #GtkStyleContexts under @screen.
GTK+ uses this to make styling information from #GtkSettings available.
Note: If both priorities are the same, A #GtkStyleProvider added through gtk_style_context_add_provider() takes precedence over another added through this function.