Is there really NO WAY AT ALL to limit the file types that are shown in a browse file window? I tried this:
It is not possible (for the programmer) to have any influence on the files dialog opened using <input type=file>
This is a security feature and nothing much can be done about it.
If you are in absolute need of this (and other functionalities like allowing multiple selects) then you have to go for a flash (or a java applet etc) implementation of the file open dialog.
There are implementations available on the net, and IIRC, there is one in YUI.
AFAIK, there is no way to do this. The next best thing would be to use JS to check the file extension before the form is submitted so the user won't waste time uploading a file that is not accepted, but the server-side file type check routine should also be kept, because the first method would be easily bypassed by turning JS off.
Here's a jQuery solution: How to have jQuery restrict file types on upload?
Hope this helps.