locator(n=0)

locator(n=1) returns the coordinates of the position of the mouse.
But you have to click the left button of the mouse.
How can I determine the mouse position without any click?
Is it possible to extend locator in a way that  
locator(n=0) outputs the coordinates at once, without any click event?

TclTk allows us to define very nice animations and demonstrations,
see for example:  demo(tkdensity). But sometimes it is much better
to have output and control in one window and to be able to respond
to changes of the cursor position (e.g. to that a bandwidth).

Thanks!

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Peter Wolf,  pwolf at wiwi.uni-bielefeld.de
Department of economics, University of Bielefeld, Germany