Since, this is effectively non-standard behavior from the application, I wanted to provide a nice visual cue on this happening. I wanted the background to appear one color, and then slowly fade to its standard color.
That would be a nice, visual cue about this new window opening. So, I went forth and tried to do it. My first attempt involved using a brush, and then just changing the opacity until it was transparent. That was utter fail. So, realizing that I wasn't as clever as I had hoped, I turned to my old friend Google.
Where I discovered a bit about Storyboards and ColorAnimation objects. Now, I'm not overtly familiar with WPF, and in fact there's quite a bit that I just don't know yet about it; but I was shocked at how easily this worked.
What I did was created 2 new SolidColorBrushes, one for the FROM color and one for the TO color. These two colors would be the beginning and ending state for the background of my control. I then shoved these into my ResourceDictionary so that a) I could easily find and manipulate them and b) utilize them elsewhere if needed.
Next, I went to the user control I was working with and created on it three new objects, a storyboard, and then two local brush objects.
Then in the method I had for loading the control and its data, I created a ColorAnimation object, cloned my two new brushes into my local brush objects, and then shoved them all together. I activated a timer, and when the timer expired, then I turned on the animation to begin the fade.
Lo, and behold, it worked! And it worked well. It's pretty, it works great as an indicator, all-in-all I was quite pleased with myself.
Anyways, the following two screencaps show the relevant code in question.
Enjoy.