With Java 1.6 and Pauker 1.8 and 1.9b2, the GUI gets messed up when repeating card.
I do the following:
* Open the attached lesson
* start repeating cards and repeat. Sometimes the bug occurs on the 2nd or 3rd card, sometimes only after around ten
* now the bottom part is empty, only the front side is shown.
* pressing "yes" still works, but pressing "yes" on the next card won't show anything, only a grey "yes" button
* sometimes it'll just take a while and react as if another "enter" has been pressed, e.g. I get shown the front side,no back side and the question "did you remember".
When cancelling repeating, clicking on a pile of cards switches off refreshing the GUI somehow, the elements do not get redrawn.
Moving the mouse over the different widgets makes them visible again. After a switch to another window and back, they are again invisible. The pile content stays invisible.
Effect occurs on Windows as well as Linux.