At some point in time you may want to remove the mirror glass from an RT/LT/RS mirror for painting or whatever. Fold a towel over once on a hard flat surface. Then SLAM the mirror down (mirror glass side down) and the mirror glass will pop out. If it doesn't then SLAM the mirror down harder.
Here's a YouTube demonstrating the technique. (The one in this video clip comes out pretty easily. Usually you need to slam the mirror down pretty hard to get the glass to pop out.)