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 style provider to context, to be used in style construction. Note that a style provider added by this function only affects the style of the widget to which context belongs. If you want to affect the style of all widgets, use gtk_style_context_add_provider_for_screen(). Note If both priorities are the same, A GtkStyleProvider added through this function takes precedence over another added through gtk_style_context_add_provider_for_screen().