dragover not working in Firefox.

Question

When I try to drag a file into Firefox (using HTML5) the dragOver event only works when I drag the file out of the window. Here's my code:

docOver: function() {
    jQuery(".whitebg[name=upload]").show();
},
docLeave: function() {
    jQuery(".whitebg[name=upload]").hide();
}

using this plugin (http://www.github.com/weixiyen/jquery-filedrop):

this.bind('dragenter', dragEnter).bind('dragover', dragOver).bind('dragleave', dragLeave);