Use Imageview SetImage Flicker

[hcyang0207]

When I use ImageView to display the camera capture frame, 15fps/second, it will flicker when updating.
imgData, err := argMat.ToImage()
if err != nil { return }
imageBitmap, err := walk.NewBitmapFromImage(imgData)
if err != nil { return }
MyUI.MainImage.SetImage(imageBitmap)