To run this test case, evaluate the following:

This opens up a window such that whenever the mouse passes over the window, the x and y position of the mouse is displayed in the upper left corner of the window. The name of the server is 'DdeExample,' and there is a topic named 'Mouse.' Under this topic there are two items 'xpos' and 'ypos.'

Next, start up Microsoft Excel and in a cell enter:

And in another cell enter:

As the mouse is moved over the Smalltalk window, the coordinates change in the spreadsheet.