refactor menu into subpackage

widgets/menu/items.go

@@ -0,0 +1,30 @@
+package menu
+
+type Item struct {
+	Val   string
+	Label string
+}
+
+// Use label as display text of item, if given
+func (m Item) Text() string {
+	if m.Label != "" {
+		return m.Label
+	}
+	return m.Val
+}
+
+type Items []Item
+
+func NewItems(items ...Item) (mitems Items) {
+	for _, i := range items {
+		mitems = append(mitems, i)
+	}
+	return mitems
+}
+
+// Sort methods for Items
+func (m Items) Len() int      { return len(m) }
+func (m Items) Swap(a, b int) { m[a], m[b] = m[b], m[a] }
+func (m Items) Less(a, b int) bool {
+	return m[a].Text() < m[b].Text()
+}