Popup move in WPF

Question

I created a WPF Popup Control on my WPF Form. When I click, the Popup Opens and it also moves properly. but when I Clicked on textbox in popup window then popup moves slightly towards the edge of main window. I don't want to move popup when I clicked on textbox in Popup?

 

Here is my code:

private void MyAddJobPopup_MouseMove(object sender,System.Windows.Input.MouseEventArgs e)
{
if (!MyAddJobPopup.IsOpen)
   MyAddJobPopup.IsOpen = true;
    if (e.LeftButton == MouseButtonState.Pressed)
   {     var mousePosition =   e.GetPosition(this.HardwareElectricalTbl);
         this.MyAddJobPopup.HorizontalOffset = mousePosition.X;
         this.MyAddJobPopup.VerticalOffset = mousePosition.Y;
   }
}