Preliminaries: in case the reader does not know already, on macOS, there’s a nice feature that makes cmd-clicking into an out-of-focus window react to a click event without bringing that window to the foreground.
In Dorico, if multiple projects are open, cmd-clicking on a tool from the background project will apply the event to all both cmd-clicked (background) and the foreground windows (only these two windows if more than 2 projects are loaded). For example, cmd-clicking on the Grid Resolution tool will change the resolution for both windows, same for the mode (writing, engraving, etc.). However, cmd-clicking on any of the note duration/articulation tools from the background project applies the duration or articulation to the foreground window only. The background project will then have as many selected tool as were clicked (see attached picture, where I was able to highlight them all!).
As the title says, it is a minor issue, but there could be unknown destructive behaviours.