ComponentOne Basic Library for UWP
DropDown for UWP Layout and Appearance

The following topics detail how to customize the C1DropDown control's layout and appearance. You can use built-in layout options to lay your controls out in panels such as Grids or Canvases. Themes allow you to customize the appearance of the drop-down box. You can also use templates to format and lay out the control and to customize the control's actions.