effects slide_in/out sometimes break resizing

After using slide_in the height of the node is set to 0. Subsequently using slide_in the scrollHeight must be obtained. In some situations the node incorrectly reports a scrollHeight of 0 and thus cannot open properly.

A solution was suggested by Thomas Herve in
http://paste.ubuntu.com/574976/

The following needs to be added to incorporated into add_slide_state_events:

For slide_in:

    anim.on("start", function() {
        node.setStyles({
            visibility: 'visible'
        });
    });
    anim.on("end", function() {
        node.setStyles({
            height: 0,
            visibility: 'hidden'
        });
    });

For slide_out:

    anim.on("start", function() {
        // Set the node to 'visible' for the beginning of the animation.
        node.setStyles({
            visibility: 'visible'
        });
    });
    anim.on("end", function() {
        // Change the height to auto when the animation completes.
        node.setStyles({
            height: 'auto'
        });
    });