I've encountered some designs in WPF apps that utilize a "fade out gradient", that is, a two stop gradient with one being 100% opaque and the other being 100% transparent.
However, often some developers have chosen to leave the "fade out" stop of the gradient to the default color. After all, it is 0% alpha, so what does it matter right? Wrong.
If working on a black background if the "fade out" stop is left to WHITE and faded out, irregular color fades occur. Same goes for a white background and a BLACK fade out stop.
Here is an example to better illustrate. We have a green gradient that fades out on the left. In the first gradient, we have a default (BLACK) fade out stop. In the second we use the same color as the visible stop for the "fade out" stop. See the difference yourself - the first gradient has black banding in the middle.
Nothing earth shattering, but keeping these little things in mind will always make your app look all the more professional.