fix: query window-size in a goroutine (#1059)

We need to run checkResize in a goroutine, otherwise, it will block.

Related: #988 (comment)
Fixes: 7d70838 (feat: add a cmd to request window size (#988))

examples/window-size/main.go

@@ -0,0 +1,44 @@
+package main
+
+// A simple program that queries and displays the window-size.
+
+import (
+	"log"
+
+	tea "github.com/charmbracelet/bubbletea"
+)
+
+func main() {
+	p := tea.NewProgram(model{})
+	if _, err := p.Run(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+type model struct{}
+
+func (m model) Init() tea.Cmd {
+	return nil
+}
+
+func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
+	switch msg := msg.(type) {
+	case tea.KeyMsg:
+		if s := msg.String(); s == "ctrl+c" || s == "q" || s == "esc" {
+			return m, tea.Quit
+		}
+
+		return m, tea.WindowSize()
+
+	case tea.WindowSizeMsg:
+		return m, tea.Printf("%dx%d", msg.Width, msg.Height)
+	}
+
+	return m, nil
+}
+
+func (m model) View() string {
+	s := "When you're done press q to quit. Press any other key to query the window-size.\n"
+
+	return s
+}

tea.go

@@ -424,7 +424,7 @@ func (p *Program) eventLoop(model Model, cmds chan Cmd) (Model, error) {
 				p.SetWindowTitle(string(msg))
 
 			case windowSizeMsg:
-				p.checkResize()
+				go p.checkResize()
 			}
 
 			// Process internal messages for the renderer.