Creating custom file dialog for bulk photo upload

Is it possible to customize the "Browse UI window" which always open when we upload photos / files? I want to acheive two things:

In the bottom it always says "All Files". I want to lock that to only .jpg, .jpeg, .png so only those files types can be selected for upload. Secondly extent that box so when the upload is complete the preview opens on right of it of the uploaded photo.

The few people I asked said it is not possible to customize that window because it is part of the OS. So my question is can we create a custom browse window using ajax, jQuery, etc to upload photo from the user's PC? The window must support cross OS support. Or any PHP plugins for this?

To do mass uploads, on Facebook/Flickr they m开发者_如何学Goake us install an ActiveX component first. Is there any other way to allow users to do mass uploads without having to install ActiveX component? Straight from the OS, or using AJAX jQuery?

If not then, are there any exiting open source plugin for this that will work with PHP? Or what other options are there so I can allow users to upload their photos in bulk?

Thanks.

You can't change the browser default.

However, you can use Flash: http://www.swfupload.org/

I've been using a ExtJS a lot lately and theres an UX from one of the core members that does just that without having to install plugins and AFAIK it has a wide range of supported browsers (all the mayor ones at least).

Check the example here: http://www.aariadne.com/uploadform/

I has very small footprint but you'll have to use the ExtJS library in other to use it.