If I press cancel, nothing happens. If a press X nothing happens. Basically the only way to cancel this action is to re-boot the DT.
If create one more bookmark i end up with two windows which I cannot close, etc.
The screenshot doesn’t look as expected, the New Bookmark panel should be attached to the main window. Which version of macOS do you use? Was any other window of DEVONthink opened?
Then I opened a DB, and the bookmark is still correctly attached to the main window.
This is definitely not the behaviour which I observed while opening this thread. The only thing I changed in the meantime is switching to dark mode on mac but I assume it should have 0 impact on this feature.