Add overlay components 176-195; pixel Harbor and Kit.Cue

Dialogs on DialogBase with focusable panels that harbor parked focus,
popovers on PopoverBase, bubbles, drawers, sheets, a lightbox, an RPG
dialogue box, notifications, a pause menu and a dithered title card.
Kit.Cue moves from feedback to pixel.

overlay/hovercard.go

@@ -0,0 +1,41 @@
+package overlay
+
+import (
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type HoverCardOptions struct {
+	// Width is the card's in dots; zero means 160.
+	Width int
+}
+
+type hoverKey struct{}
+
+// HoverCard shows card below trigger while either is hovered.
+func HoverCard(c *ui.Context, text string, o HoverCardOptions, trigger func(), card func()) *ui.Element {
+	k := pixel.K(c)
+	w := pixel.Or("HoverCard Width", o.Width, 160)
+	wrap := ui.Box(c)
+	last := ui.Local(wrap, hoverKey{}, func() ui.Rect { return ui.Rect{} })
+	b := wrap.Bounds()
+	px, py, _ := wrap.PointerPosition()
+	show := hint(c, wrap, 0) || last.Contains(b.X+px, b.Y+py)
+	wrap.Children(trigger)
+	*last = ui.Rect{}
+	if !show {
+		return wrap
+	}
+	ww, _ := c.Size()
+	ui.Overlay(c, func() {
+		e := ui.Column(c).Absolute().Left(max(0, min(b.X, ww-k.D(w)))).Top(b.Y + b.H).Width(k.D(w)).
+			Padding(k.D(6)).Role(ui.RoleGroup).Label(text)
+		*last = e.Bounds()
+		e.Draw(func(p *ui.Painter, r ui.Rect) {
+			g := k.Canvas(p, r)
+			g.Frame(0, 0, g.W, g.H, pixel.Window, pixel.Face)
+		}).Children(card)
+	})
+	return wrap
+}