Add chat components 321-345; named List rows, inert scroll views

Speech bubbles, a chat log that follows its end, a composer that sends
on Enter, typing dots, chat and channel lists, read receipts,
reactions, emoji and sticker pickers, mentions, date and unread rules,
system lines, member lists, user cards, a mailbox, mail reader and
letter, a notification bell, call controls, a voice meter, attachment
chips, link previews and polls.

pixel's editor takes EnterSends; display's Bubble takes a Fill and
exports EmojiSprite. data.List names its rows, which also lets typing
choose one. layout.ScrollArea and input.TextArea hold still under
Inert, and an inert scroll view leaves the Tab order until it wakes.

input/textarea.go

@@ -16,6 +16,8 @@ type TextAreaOptions struct {
 	// Width is zero for 160 dots, Lines zero for 4.
 	Width, Lines int
 	Disabled     bool
+	// EnterSends submits on Enter; Shift+Enter breaks lines.
+	EnterSends bool
 }
 
 type areaKey struct{}
@@ -36,7 +38,8 @@ func TextArea(c *ui.Context, text string, value *string, o TextAreaOptions) Text
 	lines := pixel.Or("TextArea Lines", o.Lines, 4)
 	col := ui.Column(c).Width(k.D(pixel.Or("TextArea Width", o.Width, 160))).Gap(k.D(2))
 	st := ui.Local(col, areaKey{}, func() areaState { return areaState{line: -1} })
-	if o.Disabled {
+	// Disabled or inert, the view holds still.
+	if o.Disabled || pixel.Current(c).Inert {
 		st.scroll.Y = st.held
 	}
 	var ed pixel.Edit
@@ -46,7 +49,7 @@ func TextArea(c *ui.Context, text string, value *string, o TextAreaOptions) Text
 			g := k.Canvas(p, r)
 			g.Frame(0, 0, g.W, g.H, pixel.Sunken, pixel.Well)
 		}).Children(func() {
-			ed = pixel.Editor(c, value, pixel.EditorOptions{Multiline: true, Label: text, Placeholder: o.Placeholder, MaxLength: o.MaxLength, Disabled: o.Disabled})
+			ed = pixel.Editor(c, value, pixel.EditorOptions{Multiline: true, Label: text, Placeholder: o.Placeholder, MaxLength: o.MaxLength, Disabled: o.Disabled, EnterSends: o.EnterSends})
 		})
 		// Keep the caret's line in view after it moves.
 		if ed.Line != st.line || *value != st.text {