This demo illustrates how to use an editor's NullText property to display prompt text (watermark) in its edit box. The NullTextDisplayMode property specifies whether the null text is displayed in the editor depending on its focus state (if the editor's value is null). Note that the null text does not display in the focused editor if a mask is applied (see the Time editor in the demo).
DevExpress editors can display a Clear button that allows you to clear the editor value when it is not empty. The DisplayMode property controls the Clear button availability.