Right clicking within most of the body/rectangle of the header (mouse pointer appears as “I”) brings up the normal menu (Undo, Redo, Cut, Copy, Paste, Delete, Select All) in the normal position relative to the header one would expect.
But right clicking on or inside near the header’s top or bottom horizontal border (mouse pointer appears as arrow) instead results in the menu normally associated with right clicking the document icon (Reveal in Binder, Path, … Lock Inspector to Editor, Lock Group View Mode) popping up way to the left and above the non-full screen Scrivener app.