Support window size and resize

main.go

@@ -73,6 +73,7 @@ func initialModel() model {
 	ti.SetVirtualCursor(false)
 	ti.SetStyles(textarea.DefaultStyles(true)) // default to dark styles.
 	ti.Focus()
+
 	ti.SetHeight(20)
 	ti.SetWidth(80)
 
@@ -106,6 +107,9 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	m.transientMsgs = newMsgs
 
 	switch msg := msg.(type) {
+	case tea.WindowSizeMsg:
+		m.textarea.SetHeight(msg.Height - 5)
+		m.textarea.SetWidth(msg.Width - 6)
 	case tea.BackgroundColorMsg:
 		// Update styling now that we know the background color.
 		m.textarea.SetStyles(textarea.DefaultStyles(msg.IsDark()))
@@ -180,7 +184,7 @@ func (m model) writeFile() error {
 
 func (m model) View() tea.View {
 	footer1 := "(ctrl+c to quit)"
-	footer2 := ""
+	footer2 := ":-)"
 
 	for _, message := range m.transientMsgs {
 		footer2 += message.msg + ", "