How to reproduce:
1. Open the Unity Editor and any pop-up menu (e.g. Gizmos menu in the Scene View)
2. Take a macOS screenshot (Cmd+Shift+5 or Cmd+Shift+4)
3. With the pop-up menu opened, click the floating screenshot thumbnail to open the full macOS Screenshot markup window
4. Observe the results
Expected results: The macOS Screenshot markup window stays in front since it's the focused window, and Unity's dropdown/popup menu appears behind it or not at all until the Screenshot window is dismissed
Actual results: The Unity dropdown/popup menu renders on top of the macOS Screenshot markup window, regardless of which menu is opened
Reproducible with: 6000.0.81f1, 6000.3.17f1, 6000.5.10f1, 6000.6.0b9, 6000.7.0a5
Reproducible on: macOS Tahoe 26 (M1)
Not reproducible on: No other environment tested
Note: Not specific to the Gizmos dropdown, it reproduces with any Unity Editor dropdown/popup menu, indicating Unity's floating menu windows ignore normal macOS window-focus/z-order rules relative to other frontmost apps