T08b menus: menu bar over the native menus, searchable menu, pie menu; megamenu points to the navigation menu; menus follow their hosts

AGENTS.md

@@ -58,7 +58,9 @@ Ely GPUI Component. A component library for GPUI, in light and dark.
 - Floating lists go below their anchor, or above when only above has room (`forms::options::float`). gpui's own switch keeps the anchor point, so a flipped list would cover its trigger.
 - A trigger that opens a list goes through `forms::select::listing`: toggle, keys, blur and popup live there, for Select, TabOverflowMenu and Breadcrumb alike.
 - A palette goes through `navigation::palette::Palette`: query field, grouped rows, cursor, keys and focus live there. CommandPalette, QuickOpen, QuickSwitcher, SearchPalette and QuickLauncher only build rows.
-- A menu goes through `menus::menu`: rows, submenus, keys, focus and presses outside live there, for DropdownMenu, OverflowMenu, SplitButton and ContextMenu.
+- A menu goes through `menus::menu`: rows, submenus, keys, focus and presses outside live there, for DropdownMenu, OverflowMenu, SplitButton, ContextMenu, SearchableMenu and MenuBar. A press on the host's own box is the host's to handle, so a trigger toggles and a right click moves a context menu without a close and reopen in one event.
+- gpui focuses the nearest focusable ancestor on mouse down, and apps wrap everything in a `FocusScope`. A press that must leave focus alone calls `prevent_default`, as buttons and context regions do.
+- gpui draws a window's first frame inside `open_window`. State the first frame reads, such as `cx.set_menus`, is set before it opens.
 - gpui clicks a focused element when Enter or Space is released. An overlay that hands focus back picks on release too; a pick on press returns focus first, and the release clicks the opener again.
 - A marker that slides between items (segment thumb, tab line) measures them with `motion::slide` and eases with `glide`.
 - A picker hands focus to its popup on open and back to its trigger on pick or Escape; it closes once focus leaves both (`forms::date::picker`).