FindFirstElementInVisualTree<T>(DependencyObject parentElement) where T : DependencyObject var count = VisualTreeHelper.GetChildrenCountreturn null;
{
var child = VisualTreeHelper.GetChild
这个:当上面的第28行时,visualtreehelper.getchildrencount返回0。GetVisualChild<T>(Visual parent) where T : Visual T child = default(T); for (int i = 0; i < numVisuals; i++) Vi