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.types.STYLE_PROVIDER_PRIORITY_FALLBACK and gtk.types.STYLE_PROVIDER_PRIORITY_USER
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.StyleContext.addProviderForScreen.
Note: If both priorities are the same, a #GtkStyleProvider added through this function takes precedence over another added through gtk.style_context.StyleContext.addProviderForScreen.