Just gonna throw this out there before I forget, but file input tags can have filters applied, which would be helpful with file submission. The filter is enabled by using the "accept" attribute, but it still allows users to select "*.* all files" and find a file with other types (can't remember name). Below is an actual example that is being used in my current alpha of Virtuoso.
<input type="file" id="file" accept=".midi,.mid" style="width:49%;display:inline-block;"/>