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
Style.contextAddProviderForScreen.
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 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 Style.contextAddProviderForScreen.
Note: If both priorities are the same, a GtkStyleProvider added through this function takes precedence over another added through Style.contextAddProviderForScreen.