I think I have found the problem. When I start the following Testscript on Vizard 2.53, the print command is executed and after that winviz quits. On Version 3 beta the print command is NOT executed before quitting. Thats why the "TextureLoaderThread" starts again and again because I need to set a flag there.
If you still need it, i will try to create a small script tomorrow that show you the exact code structure (this will take some time because i'm not the initial author of the script)
Code:
import viz
viz.go()
def mykeyboard(key):
if key == viz.KEY_ESCAPE:
print 'this will not appear on Vizard 3 beta'
viz.callback(viz.KEYBOARD_EVENT,mykeyboard)
(using the is-operator solved the problem with the exception ... ups
)