change texture size after loading - what have i to update ?

[tb77]

i'am working on a video texture feature. for streaming wmv content, initialisation time is very long (1-5 seconds per texture) so i create those textures with a small 1x1 dummy texture file - when i need the video, it is loaded on fly, but i have to update the texture size, which is no problem, but it seems that there is a redundant texture size information somewhere in cegui, which i can't find.... where is it? any strange cache?

thomas