使用WPF，更新自定义按钮控件的背景的最佳方法是什么？

In WPF, we are creating custom controls that inherit from button with completely drawn-from-scratch xaml graphics. We have a border around the entire button xaml and we'd like to use that as the location for updating the background when MouseOver=True in a trigger. What we need to know is how do we update the background of the border in this button with a gradient when the mouse hovers over it?In WPF, we are creating custom controls that in