draw_elements can't draw a element buffer object

[robn]

draw_elements wraps glDrawElements like so:

pub fn draw_elements(mode: GLenum, element_type: GLenum, indices: &[u8]) {
    unsafe {        
        return ll::glDrawElements(mode,
                                  indices.len() as GLsizei,
                                  element_type,
                                  cast::transmute(&indices[0]));
    }
}

However when drawing with an element (index) buffer object, you want to call glDrawElements more like:

    glDrawElements(mode, N, type, (void*) 0);

Where N is the number of elements in the buffer that's already been submitted.

draw_elements gives no way to do this that I can see.