public void RegisterStyleSheet(string sheetURI, uint type)
{
nsIIOService ios = Xpcom.GetService<nsIIOService>("@mozilla.org/network/io-service;1");
ios = Xpcom.QueryInterface<nsIIOService>(ios);
nsIURI ssURI = ios.NewURI(new nsAUTF8String(sheetURI), null, null);
if (StyleSheetService.sheetRegistered(ssURI, type))
return;
StyleSheetService.loadAndRegisterSheet(ssURI, type);
}