问题
I cannot assign the Visibility State to Hidden for a ProgressBar. I've read that in the WPF model, Hidden denotes a visibility state where the object should not render, but should still occupy space in a WPF layout. Silverlight does not support Hidden. Is there a workaround to get the same effect as Hidden in my app?
回答1:
Visibility.Hidden is WPF only. Both Silverlight and Windows.UI.Xaml use only Visibility.Visible or Collapsed.
You can set the UIElement's Opacity property to zero to prevent it from rendering. This value is also readily animatiable so you can fade the element in and out smoothly.
来源：https://stackoverflow.com/questions/28097153/workaround-for-visibilty-hidden-state-windows-phone-8-1-app-development