Note: This issue now excludes the discussion with Mixer Window. Even though Mixer Window is actually having the same problem, one could always use F3 or FN+F3 (according to the operating system settings) to call it out. I initially tried to talk about this issue at Dorico facebook group, but John Barron kept talking about the Mixer window, making me feel the necessity of starting a new topic here.
Some quotes of my texts from Dorico Facebook Group:
I see currently the Windows version of Dorico assigns each VST instance window a taskbar icon-buttons, offering conveniences for people to switch between Dorico window and VST plugin windows by mouse-click > or simply ALT+TAB> . Meanwhile, according to my experiences, switching between VST windows and Dorico window on macOS is not that convenient at all. I couldn’t see similar icons on the macOS Dock.
Please make sure Ctrl+Tab on macOS could help users switch all Window instances created by Dorico. The CMD+Tab is to switch among applications and Ctrl+Tab is to switch windows within an application. Dorico at this moment on macOS couldn’t do the Ctrl+Tab yet.
With that being said, the Dorico itself and its parralel VSTAudioApp are separate applications (Plus, VSTAudioApp is a hidden application which is not shown in the lists enumerated by the CMD+Tab screen), hence the necessity of an alternative approach to switch between Dorico and the VSTAudioApp. TBH I would suggest a special icon at the right of the macOS menu bar which offers a click-down menu enumerating all available VST Window processes to switch.
P.S.: This may be a bigger problem on desktop macs than that on genuine mac laptops: On MacBook laptops we could simply use finger gesture on TouchPad to trigger mission control (and it enumerates all currently-displayed Windows from all running applications). However, TouchPad is not a common equipment for desktop macs (incl. Mac Pro and Hackintoshes), and using Keyboard to trigger Mission Control is not a way as efficient as the other operations performable in Dorico (every music input is achievable by performing keyboard shortcuts).
Hope that this issue could get improved in the next major release of Dorico, alongside with the solution of the missing “audio mixdown export progress” window on macOS.