Karsten, you still haven't made it clear what the problem is.
You wrote:
"Thumnail orientation has no effect on Slideshow, Editwindow and to external programs, only in thumbnaillist."
Do you mean:
1) ..that the viewer ignores the EXIF orientation of the image?
or:
2) ..that you have rotated the thumbnail of an image, and the viewer does not adjust the orientation of the displayed image to this rotation?
Both work fine for me in TP9.
For 1., you have to set Options | Preferences | Metadata | Rotate based on XMP/EXIF orientation
For 2., you have to set Options | Viewing | Other | Use database thumbnail orientation when displaying images
Note: If you are working with raw camera files, and you want them to be converted to the proper orientation, you should also look in the Digicam or DCRaw plug-in options.