Keyboard won't dismiss even after Focus change

Question

I am creating a Windows 8.1 app and after the user presses a button, a popup opens over most of the screen. There are several textboxes inside the popover.

I found

Answer 1

When the textbox that shows the virtual keyboard was disabled it will dismiss the virtual keyboard. so the solution is set the textbox property IsEnabled to false and set it again to true so it can be use again.

TextBox.KeyDown += (s, a) => {
 if (a.Key == VirtualKey.Enter) {
   TextBox.IsEnabled = false;
   TextBox.IsEnabled = true;
 }