Widget upload-url: could you add a <label></label> next to the <input type='file' /> ?

The upload-url-xyz widget generates an input[type='text'] and an input[type='file'] as expected.

But I can't customise it. To customise, I need a <label></label> element like this:

<input type="file" name="file" id="file" class="inputfile" />
<label for="file">Choose a file</label>

I discussed it with @jbpasquier for another problem and he said it's a common use to add a label then customise it and hide input.