Thanks for testing. I still haven't been able to reproduce this here.
If you set Windows to light mode, then run beta, and then close the DCC Send/Get window by clicking the "Close" button, do you see the same issue?
I assume that this does not happen for you with v7.78?
I am also testing beta version 7.78.6786 on Windows 11 Pro 24H2 (OS build
26100.2605) the DCC Send/Get and have not been able to reproduce this bug in both light/dark modes.
I also tested it in version 7.78 and was unable to reproduce it.