title: Custom Brush - I want two gradients chaining them together
body: <p>I am making a bar chart and I want two separate gradients for each bar. First I want a gradient to go from top to bottom solid red to transparent red. I want to paint over the top of that a gradient that goes from right to left, black to opaque.</p>
  
  <p>So - In the bottom left we should have;</p>
  
  <ul>
  <li>Bottom left - Alpha 0</li>
  <li>Bottom right - Alpha 0</li>
  <li>Top left - Alpha 255 Colour Red</li>
  <li>Top Right - Alpha 255 Colour Black</li>
  </ul>
  
  <p>So in effect I want to take a solid colour, add a left to right gradient to black then take the output of that and add a top to bottom gradient to transparency.</p>
  
  <p>All this and I want it to be in a single brush, is this even possible?</p>