code: func (v *StyleContext) GetStyleProperty(property string) (interface{}, error) {
  	cstr := (*C.gchar)(C.CString(property))
  	defer C.free(unsafe.Pointer(cstr))
  
  	var gval C.GValue
  	C.gtk_style_context_get_style_property(v.native(), cstr, &gval)
  	val := glib.ValueFromNative(unsafe.Pointer(&gval))
  	return val.GoValue()
  }
docs: // GetStyleProperty is a wrapper around gtk_style_context_get_style_property().