Yes! The align="center" on the textfield plugin caused the weird placement during resize. Removed the alignment, and it worked.
Also managed to link the size to it's parent container. (layer[blok2].width) <- wich has a 80% width.
The white stripe was caused by the fact that the textfield layer had no width and height. I've set width to 100% and height to it's initial iframe height: 360.
_____________________
var myframe = document.getElementById("myframe");
var calcValX = krpano.get("layer[blok2].width");
myframe.style.width = calcValX + "px";
_____________________
So far it seems that it is working. Thanks for starting this topic and the little hind @Umalo!
There might be better/cleaner ways to make it relative to a container. Any tips about that are welcome! But for now it works
I'll post the url of the tour as soon as it is finished. If you would like to see how it works in the meanwhile, just PM me.