well, I've been trying this on virtual machine, always works ok. You have to *carefully* approach the popup from the right and click on the popup's right border to get the scroll visible. This evening I'll check the behavior on my DR800.
Another thing that bothers me: when you move stylus close enough but still do not touch the screen a popup window moves with the stylus .. Looks like popup is grabbed by a cursor = you click and drag the popup window while holding the mouse button pressed.
Popup may disappear as long as it "sees" you move your mouse = you are done with translation. So after underlying you have to be careful with having your stylus close enough to the screen ..
I'll check what is possible to do on the "stabilization" of popup.