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/spotlight.go

@@ -0,0 +1,36 @@
+package overlay
+
+import (
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type SpotlightOptions struct{}
+
+// Spotlight dithers all but target and captions it.
+func Spotlight(c *ui.Context, target *ui.Element, caption string, o SpotlightOptions) *ui.Element {
+	k := pixel.K(c)
+	b := target.Bounds()
+	deep, _ := dark(k)
+	var veil *ui.Element
+	ui.Overlay(c, func() {
+		veil = ui.Box(c).Absolute().Left(0).Top(0).Right(0).Bottom(0).PassThrough().Role(ui.RoleStatus).Label(caption)
+		veil.Draw(func(p *ui.Painter, r ui.Rect) {
+			g := k.Canvas(p, r)
+			// The hole is the target, two dots wider all round.
+			x, y := int(b.X/k.Dot())-2, int(b.Y/k.Dot())-2
+			w, h := int(b.W/k.Dot())+4, int(b.H/k.Dot())+4
+			g.Veil(0, 0, g.W, y, deep, 12)
+			g.Veil(0, y+h, g.W, g.H-y-h, deep, 12)
+			g.Veil(0, y, x, h, deep, 12)
+			g.Veil(x+w, y, g.W-x-w, h, deep, 12)
+			g.FocusMark(x+2, y+2, w-4, h-4)
+		})
+	})
+	w := pixel.Measure(caption) + 16
+	bubble(c, ui.Rect{X: b.X, Y: b.Y - k.D(2), W: b.W, H: b.H + k.D(4)}, func() {
+		pixel.Text(c, caption, pixel.TextOptions{})
+	}, w)
+	return veil
+}