plupload uses something like this input type="file"

<input id=​"html5_197263a5ok7gmcou4a2q512e05" type=​"file" style=​"font-size:​ 999px;​ opacity:​ 0;​ position:​ absolute;​ top:​ 0px;​ left:​ 0px;​ width:​ 100%;​ height:​ 100%;​" multiple accept>​

inside a DIV with class="moxie-shim moxie-shim-html5" and 0 dimensions:

style="position: absolute; top: 0px; left: 0px; width: 0px; height: 0px; overflow: hidden; z-index: 0;"

Navigate this page with the Tab key on your keyboard: all tested browsers focus all the fields except Safari which skips the invisible (or semi-invisible) ones (Firefox doesn't show the focus styles, but it does focus all the fields).

in the markup

in the markup invisible

JS generated

JS generated invisible