Text drawing - an extension interface. It offfers DrawLine(), DrawText() and DrawRect() methods. The idea is to move out from RTm<Name>Interpreter implementations all CGraphicsContext::Draw<Item> calls and replace them with the corresponding MTmTextDrawExt::Draw<Item> calls. The implementations of MTmTextDrawExt interface can customize drawing methods implementations - for example - including opaque drawing support. The MTmTextDrawExt interface UID is KTmTextDrawExtId. The interface implementation can be queried through a MTmSource::GetExtendedInterface() call.