gl::ScopedScissor and window matrices

Hey there,

because the y axis is flipped in 2D mode ( setMatricesWindow(…) ) by default in cinder, using gl::scissor is a bit confusing. I always have to do some math the get it right. Like so:

        auto pos = vec2( 100, 100);
        auto size = (mRect.getSize());
        auto invPos = vec2( (pos.x), (getWindowHeight()) - (pos.y) - (size.y) );
        gl::ScopedScissor sC( toPixels( invPos  ),  toPixels(size) );

I was wondering, is there a more correct/convenient way of doing this?