Thanks to all.
Yep, after I saw those borders (just for the memory: it's one pixel...) I went thru some uploaded pics as well and have found several pics, not just mine, with that border.
If you want to avoid it, first resize to an imagesize 2 pixels wider and higher, than the end size (example: 1026X770 for pics with a endsize of 1024x768) and resize again at the end after all your work on the pic.
I don't know, if this happens with all graphic softwares. I use Photoshop LE, for those interested.
And BTW: YEP, Jan is right, I tried to get those lamp posts straight, hoping, the result would be ok
dominguez(dash)online(dot)ch ... Pushing the limits of my equipment