Add goroutine6

Ported from:
https://github.com/therecipe/examples/blob/master/advanced/widgets/goroutine/main.go

.gitignore

@@ -20,6 +20,7 @@ cmd/genbindings/genbindings
 cmd/miqt-uic/miqt-uic
 cmd/miqt-rcc/miqt-rcc
 
+examples/goroutine6/goroutine6
 examples/helloworld/helloworld
 examples/helloworld6/helloworld6
 examples/mdoutliner/mdoutliner

examples/goroutine6/main.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"time"
+
+	qt "github.com/mappu/miqt/qt6"
+)
+
+func main() {
+	qt.NewQApplication(os.Args)
+
+	window := qt.NewQMainWindow2()
+	window.QWidget.SetFixedSize2(250, 200)
+	window.QWidget.SetWindowTitle("goroutine Example")
+
+	widget := qt.NewQWidget(window.QWidget)
+	var layout = qt.NewQVBoxLayout2()
+	widget.SetLayout(layout.QBoxLayout.QLayout)
+	window.SetCentralWidget(widget)
+
+	labels := make([]*qt.QLabel, 3)
+	for i := range labels {
+		label := qt.NewQLabel(window.QWidget)
+		label.SetAlignment(qt.AlignCenter)
+		widget.Layout().AddWidget(label.QWidget)
+		labels[i] = label
+	}
+
+	button := qt.NewQPushButton5("start!", window.QWidget)
+	button.OnClicked1(func(bool) {
+		button.SetDisabled(true)
+		for i, label := range labels {
+			go func(index int, qlabel *qt.QLabel) {
+				var tick int
+				for range time.NewTicker(time.Duration((index+1)*10) * time.Millisecond).C {
+					tick++
+					time.Sleep(50 * time.Millisecond)
+					qlabel.SetText(fmt.Sprintf("%v %v", tick, time.Now().UTC().Format("15:04:05.0000")))
+				}
+			}(i, label)
+		}
+	})
+	widget.Layout().AddWidget(button.QAbstractButton.QWidget)
+
+	window.Show()
+
+	qt.QApplication_Exec()
+}