Hi,
the problem was in a completely other area.
When opening the map, I had following 2 lines:
<action name="showmap" >
..
tween(area.x,100%);
tween(area.width,0%);
..
</action>
I deleted those two lines from my code; and now it works as supposed.
I admit, that I do not fully understand what happened (I asume, the map should shift the pano away - which it really does).
Those two lines I had copied a long time ago from a very early map-example and it did not harm my code under flash.
Regards