View-first editor opening.
A plug-in host creates the editor view synchronously and shows nothing of it – in Logic, a header-only plug-in window – until that call returns. While one of these is alive on the calling thread, ScriptedUiSession::load_deferrable() does not evaluate the document: it checks the script can be read, returns true, and evaluates it from the session's second poll(), so the host gets a correctly sized view at once and the first frame paints before the document mounts. ViewBridge::open() holds one for every host-embedded editor (ViewBridge::Options::hosted_editor()), around both create_view() and the default scripted editor. A plain load() inside one still evaluates immediately – its caller may read bridge() next – but warns once when that blocks the host. Standalone hosts and in-process harnesses never hold one, so their document is mounted when either returns.
1.15.0