The mouse enter and leave events are not available on devices (along with many other events that are available on the desktop) so it is not possible to implement them. They were presumably omitted to save space, it is the "Compact" Framework, as devices are intended to be used with a stylus or finger for which the enter/leave paradigm is not really applicable. MouseDown, MouseMove and MouseUp events are available on some controls and can be implemented with the Door library if they are required.