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new button()

    var b = new button(text,function,<x>,<y>,<refDiv>)

creates a button with text and function, x-y position (optional), and a DHTML element to which x and y are relative (optional)
text can be:

- plain text
- HTML text
- a DHTML element, including complete DIVSs and SPANs that have been previously defined in the HTML page
- an image (text ending on .gif, .png or .jpg)
- a MapClient object, like a slider

The function can be:

- a regular Javascript function. This is called with the button object itself as first parameter
- a menu. When the button is clicked, the menu will pop up after a small interval at the appropriate side of the button
- null, e.g. when the button has internal DHTML items with their own events defined

Like all MapClient objects, a button's internal layout properties can be accessed by its "div" property. For a button called b, the text is "b.div.innerHTML", its color "b.div.style.color", etc
Buttons are mostly created to be included in a menu, but they can be created on their own too. Only then do the three last parameters make sense. They give its position in pixels or percent values, relative to the document, or to a specified DHTML element. In
11 buttons are created to show the different possibilities