I use a trackball as a computing pointing device (see [this Lifehacks SE questions for the model and a couple photographs](https://lifehacks.stackexchange.com/questions/23490/how-to-reduce-accidentally-pressing-the-right-button-on-a-trackball)). The rubber feet on the bottom of the trackball frequently come off during use. Once this happens, it slides around on the desk and damages the desk's surface.

To try to mitigate these problems, I tried putting a rubber mat under the trackball. It protects the desk, but the trackball still slides around quite a bit. Also, the mat slides around.

I've also tried re-gluing the rubber feet to the plastic trackball housing. So far, nothing has worked good enough to prevent the rubber feet from becoming dislodged within a fortnight.

What can done to effectively resolve this issue once and for all?