It worked, thanks. Additionaly I had to Dispose the Textureobject afterwards, otherwise i got null exception after some time using activiz.
If the textureobject would be used by another actor this procedure would be fatal? Can I reduce textureobjects referencecount instead by one before SetTexture(null), like this:
int currentCount=actor.GetTexture.GetReferenceCount();
actor.GetTexture.SetReferenceCount(currentCount-1);
actor.SetTexture(null);
If I Dispose the actors textureobject before setting null, will the underlyinder imagedata also be deleted?