Widgets on Desktop Are Visible on Transparent Windows in Fullscreen

When using macOS's fullscreen the widgets on the desktop bleed through transparent windows I saw from an earlier report that this behavior isn't intended as you fixed the background being visible when in full screen.

Start by reproducing the issue on macOS with fullscreen enabled and a transparent window, using the attached screenshot as the expected symptom. Read the earlier fullscreen background fix referenced in the report and trace the relevant window and desktop rendering path; done means desktop widgets no longer bleed through transparent fullscreen windows.

Written by the indexing model from the issue text.