Also reproduced on 1.7.90 release

I can confirm this on Ubuntu 19.04

I can confirm this on Win10 as well.

Problem is in MainWindow.java:

historyButtonPanel.setPreferredSize(new Dimension(300, 10));

The button row has a preferred height of 10, which must be a mistake. I think that any time the button row "disappears", it's the row getting it's preferred size, which is too small to actually render any of the buttons.

Just removing that line fixes the issue. Is there any particular reason why the preferred size of the row of buttons needs to be hard coded? If that's the case then picking a more appropriate preferred height for the row also fixes the issue.

Seems like an easy fix then?