Add code components 366-385; ScrollArea Follow, editor sync

A terminal with history, a Go-colored code block, a log viewer that
follows, a hex viewer, a memory map, a JSON tree, a line diff, a GAME
OVER crash screen, an FPS meter, profiler bars, breakpoints,
variables, command history, a shortcut list, a debug grid, a pixel
editor that exports string art, a palette editor, a sprite sheet, a
glyph map and a 6502 register view.

layout.ScrollArea takes Follow, and ChatLog now uses it. data.TreeNode
takes a Value drawn in its Slot. pixel gains Has, and Sprite.Art
writes MustSprite art. pixel.Editor takes the caller's value at each
input event, so a value changed between frames is never typed onto.

code/crashscreen.go

@@ -0,0 +1,56 @@
+package code
+
+import (
+	"log/slog"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/input"
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type CrashScreenOptions struct {
+	// Width is in dots; zero means 260.
+	Width    int
+	Disabled bool
+}
+
+type CrashScreenResult struct {
+	Element  *ui.Element
+	Continue bool
+}
+
+// CrashScreen frames an error and its stack; CONTINUE goes on.
+func CrashScreen(c *ui.Context, err string, stack []string, o CrashScreenOptions) CrashScreenResult {
+	k := pixel.K(c)
+	if err == "" {
+		panic("code: CrashScreen needs an error")
+	}
+	body, ink, dim := dark(k)
+	var res CrashScreenResult
+	res.Element = ui.Column(c).Width(k.D(pixel.Or("CrashScreen Width", o.Width, 260))).Padding(k.D(8)).Gap(k.D(4)).
+		Role(ui.RoleGroup).Label(k.Msg("game_over")).Draw(func(p *ui.Painter, r ui.Rect) {
+		g := k.Canvas(p, r)
+		g.Rect(0, 0, g.W, g.H, body)
+		// The red frame blinks each second, as the guru's did.
+		if g.Step(4)%4 < 2 {
+			g.Rect(0, 0, g.W, 3, pixel.Bad)
+			g.Rect(0, g.H-3, g.W, 3, pixel.Bad)
+			g.Rect(0, 0, 3, g.H, pixel.Bad)
+			g.Rect(g.W-3, 0, 3, g.H, pixel.Bad)
+		}
+	}).Children(func() {
+		pixel.Text(c, k.Msg("game_over"), pixel.TextOptions{Slot: pixel.Bad})
+		pixel.Text(c, err, pixel.TextOptions{Slot: ink, Wrap: true})
+		for _, f := range stack {
+			pixel.Text(c, "  "+f, pixel.TextOptions{Slot: dim, MaxLines: 1})
+		}
+		ui.Row(c).Padding(k.D(4), 0, 0, 0).Children(func() {
+			res.Continue = input.Button(c, k.Msg("continue"), input.ButtonOptions{Variant: input.Primary, Disabled: o.Disabled}).Clicked
+		})
+	})
+	if res.Continue {
+		slog.Debug("8bit: crash screen continue", "error", err)
+	}
+	return res
+}