Losing MouseUp event if releasing not over the same element

I have got a problem with a slider. When i grab the handler, i change the .src of the image, just to change its color. However, i want it to change back to the original color when i release the mouse button. I have tried two things.

1) Changing it back on the handler mouseup event: this works only if i release the button over the handler, so this is not a solution.

2)Changin it back on the window mouseup event: the event is not firing properly. If i click and release on any place of the window, the event fires normaly, but if i click in the handler, move the cursor to any other point of the window, and then release the button, the event will not fire.

Btw, im using the p开发者_JS百科rototype js framework.

Solutions? Thanks

Here is the code. I load the handler function when the document is ready.

function handler()
{

    var handler = $('handler');

    Event.observe(window, "mouseup", function(){
        alert('salta');   //to see when mouseup fires
        if(handler.src=='http://localhost/moodle/blocks/videoavatar/eggface/trunk/gripper_o.png'){    //orange
            handler.src='http://localhost/moodle/blocks/videoavatar/eggface/trunk/gripper.png';}    //grey
    });


    Event.observe(handler,'mousedown',function(){handler.src='http://localhost/moodle/blocks/videoavatar/eggface/trunk/gripper_o.png';});    //orange

}

You should be attaching the mouseup handler to the document object.

How about onmouseout event?

Here is the code. I load the handler function when the document is ready.

function handler()
{

    var handler = $('handler');

    Event.observe(window, "mouseup", function(){
        alert('salta');   //to see when mouseup fires
        if(handler.src=='http://localhost/moodle/blocks/videoavatar/eggface/trunk/gripper_o.png'){    //orange
            handler.src='http://localhost/moodle/blocks/videoavatar/eggface/trunk/gripper.png';}    //grey
    });


    Event.observe(handler,'mousedown',function(){handler.src='http://localhost/moodle/blocks/videoavatar/eggface/trunk/gripper_o.png';});    //orange

}