Buttons on RC4 Series 3 devices can invoke different features by operating the buttons in different ways.  One way is to press and hold a button for several seconds.  This is called a long-press.

When using long-press features, care must be taken to avoid accidentally slipping in a way that produces a button tap rather than long-press.  When this happens, the feature that is assigned to a tap will be invoked, rather than the desired long-press function.