Panel in ScrolledWindow disappears when frame is maximized

I have an issue I can’t figure out. I have created a simple program with a scrolledwindow. Inside the scrolledwindow is a panel with statictext widgets. If, at run time, I resize the window so that it is too small to show the whole panel (vertical scrollbar is active), then click the maximize button, the panel will disappear.

example.py (1.92 KB)

It seems to have been a bug in 2.8. The problem doesn’t exist in 3.0