Microsoft granted patent for double click

United States Patent: 6,727,830 abstract: A method and system are provided for extending the functionality of application buttons on a limited resource computing device. Alternative application functions are launched based on the length of time an application button is pressed. A default function for an application is launched if the button is pressed for a short, i.e., normal, period of time. An alternative function of the application is launched if the button is pressed for a long, (e.g., at least one second), period of time. Still another function can be launched if the application button is pressed multiple times within a short period of time, e.g., double click.

Get ready to pay M$ every time you write a UI with double click :-)