Via Chris Steen:
In my button we will change the color of the canvas in on mouse hover, and allows you to implement the click logic at the TODO.
You can use this code for your own buttons.
The important points are:
MouseEnter - When we hover over the button
MouseLeave - When we stop hovering over the button
MouseLeftButtonDown - When you hold the mouse left button down
MouseLeftButtonUp - When you release the mouse left button.
A click is only considered a click, when you are hovered over the button, and the MouseLeftButtonUp.
Check out the full post on creating a Silverlight 1.1 button for full XAML and C# code.