The Triggering Event

We must now detect the event that will trigger the moving of the info box, namely the mouse-moving event. But guess what... Netscape Navigator and Internet Explorer do not support this event in the same way:

26: if (ns) document.captureEvents(Event.MOUSEMOVE);
27: document.onmousemove = get_mouse;

With Netscape Navigator, an additional instruction is required for capturing events (captureEvents). This is done on line 26.

The instruction line 27 suffices to make the execution flow jump to the get_mouse() function that positions the info box layer as soon as the mouse pointer is moved.