JabRef version

Latest development branch build (please note build date below)

Operating system

GNU / Linux

Details on version and operating system

JabRef 5.4--2021-09-01--69550d3 Linux 4.19.0-17-amd64 amd64 Java 16.0.2 JavaFX 16+8

Checked with the latest development build

• I made a backup of my libraries before testing the latest development version.
• I have tested the latest development version and the problem persists

Steps to reproduce the behavior

In dark theme:

• At the bottom of the group interface, the button Add group is, at first, very visible (too much I would say):
  

• Then (after some time, or after creating a subgroup?), the appearance of this button is modified, and it looks like it is inactivated (black characters on grey background):
  

I would expect the Add group button to look like the Search button.

Appendix

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