Unless my mind is playing tricks on me, it seems the background colour for my groups in the three-pane view is suddenly bright white, whereas before I could have sworn it was a slightly dark grey. Screenshot attached.
I’ve played around with system settings (e.g., reduced transparency) but no luck. Appears the same in both light or dark mode (OS).
It is just me or has it been this way and I’ve just not noticed it?
Yes, it changed in Mojave, due to system settings (which are different than High Sierra’s). The next major release will not be dependent on the system settings.
For now, in 10.14 or 10.14.1, change “Highlight Color” in System Preferences > General to whatever color you wish. DEVONthink will (currently) pick up the change. Be aware, this affects lots of controls across you Mac so you might not want do too much tweaking.
The next maintenance release will fix this.