Unfortunately, these polylines are draggable. I didn't find where to disable this possibility (useful in some case :) ). So How to choose enable/ disable that ?
Unfortunately disabling drag and drop is not supported the OpenLayers API version the TWebSOMaps is based on. As a workaround you can set the Allow var parameter of the OnPolylineDragEnd event to False to make the polyline snap back to it's original position.