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 Since 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.