I just created a little thing, which might be useful for others as well

Just put a List component into your Library (drag it on stage, then delete) and insert this code into the main timeline (not into the timeline of the component!).
import mx.managers.DepthManager;
list=Array({label:"Bilderdienst",data:"http://www.dibidi.de"},{label:"phn",data:"http://www.prohelpnet.de"});
l1=createChildAtDepth("List",DepthManager.kTop,{_x:100,_y:150,dataProvider:list,onChange:ausgabe,vScrollPolicy:"auto",backgroundColor:0xccddff,_alpha:50});
l1.setSize(100,list.length*25);
l1.addEventListener("change",readUrl);
function readUrl(){
getURL(l1.selectedItem.data);
}
You can enter into the list array, whatever pleases you.
If it bcomes a few entries, you will need to handle the size.
If you limit the size of the listbox, you will get a scrollbar, if you have more entries.
Have fun playing around