I generally create quite high fidelity mockups for my users to get a good idea what the final UI will look like. I am trying to create a UI with Windows 10-like styling. In the example below, I have textboxes and dropdowns with a two pixel border. To get the fidelity I require I am carefully positioning additional rectangles to extend the border.
What would be really useful if there could be a border thickness control so I could quickly set to 2 pixels.