add optional tooltip to menu widget

menus.go

@@ -129,6 +129,7 @@ func ColumnsMenu() MenuFn {
 	m.Selectable = true
 	m.SortItems = false
 	m.BorderLabel = "Columns"
+	//m.SubText = "Enabled Columns"
 
 	rebuild := func() {
 		// get padding for right alignment of enabled status

widgets/menu/main.go

@@ -11,13 +11,14 @@ type Padding [2]int // x,y padding
 type Menu struct {
 	ui.Block
 	SortItems   bool   // enable automatic sorting of menu items
+	Selectable  bool   // whether menu is navigable
 	SubText     string // optional text to display before items
 	TextFgColor ui.Attribute
 	TextBgColor ui.Attribute
-	Selectable  bool
 	cursorPos   int
 	items       Items
 	padding     Padding
+	toolTip     *ToolTip
 }
 
 func NewMenu() *Menu {
@@ -71,13 +72,9 @@ func (m *Menu) SetCursor(s string) (success bool) {
 	return false
 }
 
-// Sort menu items(if enabled) and re-calculate window size
-func (m *Menu) refresh() {
-	if m.SortItems {
-		sort.Sort(m.items)
-	}
-	m.calcSize()
-	ui.Render(m)
+// SetToolTip sets an optional tooltip string to show at bottom of screen
+func (m *Menu) SetToolTip(lines ...string) {
+	m.toolTip = NewToolTip(lines...)
 }
 
 func (m *Menu) SelectedItem() Item {
@@ -117,6 +114,10 @@ func (m *Menu) Buffer() ui.Buffer {
 		}
 	}
 
+	if m.toolTip != nil {
+		buf.Merge(m.toolTip.Buffer())
+	}
+
 	return buf
 }
 
@@ -134,6 +135,15 @@ func (m *Menu) Down() {
 	}
 }
 
+// Sort menu items(if enabled) and re-calculate window size
+func (m *Menu) refresh() {
+	if m.SortItems {
+		sort.Sort(m.items)
+	}
+	m.calcSize()
+	ui.Render(m)
+}
+
 // Set width and height based on menu items
 func (m *Menu) calcSize() {
 	m.Width = 7 // minimum width

widgets/menu/tooltip.go

@@ -0,0 +1,55 @@
+package menu
+
+import (
+	ui "github.com/gizak/termui"
+)
+
+type ToolTip struct {
+	ui.Block
+	Lines       []string
+	TextFgColor ui.Attribute
+	TextBgColor ui.Attribute
+	padding     Padding
+}
+
+func NewToolTip(lines ...string) *ToolTip {
+	t := &ToolTip{
+		Block:       *ui.NewBlock(),
+		Lines:       lines,
+		TextFgColor: ui.ThemeAttr("menu.text.fg"),
+		TextBgColor: ui.ThemeAttr("menu.text.bg"),
+		padding:     Padding{2, 1},
+	}
+	t.BorderFg = ui.ThemeAttr("menu.border.fg")
+	t.BorderLabelFg = ui.ThemeAttr("menu.label.fg")
+	t.X = 1
+	t.Align()
+	return t
+}
+
+func (t *ToolTip) Buffer() ui.Buffer {
+	var cell ui.Cell
+	buf := t.Block.Buffer()
+
+	y := t.Y + t.padding[1]
+
+	for n, line := range t.Lines {
+		x := t.X + t.padding[0]
+		for _, ch := range line {
+			cell = ui.Cell{Ch: ch, Fg: t.TextFgColor, Bg: t.TextBgColor}
+			buf.Set(x, y+n, cell)
+			x++
+		}
+	}
+
+	return buf
+}
+
+// Set width and height based on screen size
+func (t *ToolTip) Align() {
+	t.Width = ui.TermWidth() - (t.padding[0] * 2)
+	t.Height = len(t.Lines) + (t.padding[1] * 2)
+	t.Y = ui.TermHeight() - t.Height
+
+	t.Block.Align()
+}