コード
function setEventsCatch(){
if (document.all || document.getElementById) {
document.onmousedown=mouseDown;
} else if (document.layers) {
document.captureEvents(Event.MOUSEDOWN);
document.onmousedown=mouseDown;
}
}
function mouseDown(e){
if (document.all) {
if (event.button == 1) {
window.document.bgColor = "#ccccff";
}else if (event.button == 2 || event.button == 3){
window.document.bgColor = "#ffcccc";
}
} else {
if (e.which == 1) {
window.document.bgColor = "#ccccff";
} else if (e.which == 3) {
window.document.bgColor = "#ffcccc";
}
}
}