title: Highlighter Pen in c#
body: <p>I want to make it so my pen can be a highlighter, so basically changing its opacity, but i don't know how to do this. I currently use a colordialog to allow the use to choose desired colour but this only allows me have colours which aren't transparent enough to see through it like a highlighter tool on powerpoint as an example of the tool opacity. So any code to allow me to integrate the use of my colordialog with a opacity to be able to see through it.</p>
  
  <p>Thanks</p>