Drop-down Selection Control - Windows 8 Metro - XAML
I suppose you are looking for Combo box: Windows 8 store controls list (MSDN) . To use:
<ComboBox x:Name="comboBox1" SelectionChanged="ComboBox_SelectionChanged" Width="100"> <x:String>Item 1</x:String> <x:String>Item 2</x:String> <x:String>Item 3</x:String> </ComboBox>
you would have to use Popup. Below link might help you
http://rahulpnath.com/blog/windows-8-series-drop-down-button/