Whether this renderer is the main window — the one that draws the top-level menu. On Windows
and Linux, secondary windows get identical chrome minus that menu; on macOS the top-level menu
lives in the OS-level menu bar rather than in-window, so this flag does not remove it there —
every window can still reach it through the system menu bar, which is process-global and cannot
differ per window.
Set from the URL search params in the renderer process, and undefined everywhere else: the
main process and the extension host never assign it, and neither does the web view prelude, so
code outside a renderer must not read this as a reliable false.
Fixed at window creation and never updated, so it cannot describe a window becoming the main
one later (for instance after the main window closes). PT-4278's window-manager service is the
durable answer; replace this when it lands.
Whether this renderer is the main window — the one that draws the top-level menu. On Windows and Linux, secondary windows get identical chrome minus that menu; on macOS the top-level menu lives in the OS-level menu bar rather than in-window, so this flag does not remove it there — every window can still reach it through the system menu bar, which is process-global and cannot differ per window.
Set from the URL search params in the renderer process, and
undefinedeverywhere else: the main process and the extension host never assign it, and neither does the web view prelude, so code outside a renderer must not read this as a reliablefalse.Fixed at window creation and never updated, so it cannot describe a window becoming the main one later (for instance after the main window closes). PT-4278's window-manager service is the durable answer; replace this when it lands.