title: How to implement a speech bubble custom border in SL with a movable leader
body: <p>Check out the following pic. This happens when you expand a folder in Mac OS X from its shortcut on the dock. I'd like to do something very similar in SL. And in case it's difficult to understand - the dock is on the right, with the folder-speech-bubble expanding up &amp; out to the left. The folder contents would be icons out of frame in the upper-left.</p>
  
  <p><img src="https://i.stack.imgur.com/AiTIT.png" alt="Mac OS X dock folder expansion"></p>
  
  <p>The best I've come up with is including a xaml Path that makes up the "leader" portion of the bubble and placing it directly over the border of a canvas.  It looks like the following.</p>
  
  <p><img src="https://i.stack.imgur.com/9L07Z.png" alt="Silverlight speech bubble"></p>
  
  <p>The Path, being a separate element, doesn't "integrate" well with the Grid and causes two issues. If you look closely you'll see that there is a slight transparency and the Grid's border is subtly bleeding through. Something else that will crop up, if I use a border thickness > 1, is the line-end caps between the Path border and the Grid border won't be connected, they'll simply overlap looking chunky and unpolished.</p>
  
  <p>What I need is a solution that allows me to slide the leader up &amp; down the speech bubble (depending upon its context) and adapts to the issues explained above. I'd be happy with ideas, examples, and down right full implementations.</p>