WPF - How Can I make a custom Border

问题:

How Can I make a custom Border like this:

i want use a Polygon at the top of border but i don't know how do it :(

回答1:

You need to create a custom Decorator. See the following link for an example of how to do it: http://blog.pixelingene.com/2007/06/balloondecorator-source-code/