gtk/style.go
func (v *StyleContext) GetProperty(property string, state StateFlags) (interface{}, error) {
	cstr := (*C.gchar)(C.CString(property))
	defer C.free(unsafe.Pointer(cstr))

	var gval C.GValue
	C.gtk_style_context_get_property(v.native(), cstr, C.GtkStateFlags(state), &gval)
	val := glib.ValueFromNative(unsafe.Pointer(&gval))
	return val.GoValue()
}
func (v *StyleContext) GetProperty(property string, state StateFlags) (interface{}, error) {
	cstr := (*C.gchar)(C.CString(property))
	defer C.free(unsafe.Pointer(cstr))

	var gval C.GValue
	C.gtk_style_context_get_property(v.native(), cstr, C.GtkStateFlags(state), &gval)
	val := glib.ValueFromNative(unsafe.Pointer(&gval))
	return val.GoValue()
}
// GetProperty is a wrapper around gtk_style_context_get_property().