类型 DropdownMenuOptions

type DropdownMenuOptions struct {
	Layer     uint16
	Scope     ui.ID
	DismissID ui.ID
	// ID names the menu for its entrance and exit when DismissID, the default,
	// does not tell it from another menu painted under the same Scope. Side is
	// the edge of its anchor the menu opens on (the zero value is under it), which
	// is the edge it slides in from. End has to be called for the menu to animate.
	ID   ui.ID
	Side OverlaySide
	// Viewport, with DismissID, makes the menu declare a hit over the whole
	// window behind its surface, so pressing anywhere outside it reports
	// DismissID (Escape reports it too). The menu is also kept inside it: shifted
	// back when it sticks out, and shortened, so that it scrolls, when it is taller
	// than the window. Leave it empty to dismiss only on Escape and handle outside
	// presses yourself.
	Viewport ui.Rect
	// Scroll is the scroll position of a menu whose items do not all fit its
	// bounds (see MenuScroll). Without one such a menu shows only the items at
	// its top.
	Scroll *MenuScroll
	// Submenu makes this the content of a submenu, which has a smaller minimum
	// width (96) than a menu opened by a trigger (128).
	Submenu bool
}