Control Behavior Overrides - Customizing The Data Picker and Edit-Combo Behavior on a Phone
The UX component allows you to customize the behavior of certain controls based on the screen size of the device. For example, normally, the 'picker' for a date control, or an edit-combo control opens in a drop-down window, immediately under the control.
However, on a phone, which has a narrow screen, there is not enough room to display the control's 'picker' in a dropdown window. Instead, you are likely to want the control to appear in a window that is docked to the bottom of the screen, centered horizontally.