I was trying to adjust to the extra width of the IBM Model M Keyboard. The reach to the mouse was too long. I tried it on the left side of the keyboard but it was awkward and the mouse pad kept moving around. I thought, "Maybe if I use a place mat as a mouse pad, I can put it partially under the keyboard to hold it in place". I tried it but then the keyboard was wobbly. I sat and looked at it for a few minutes and suddenly a flashbulb went off over my head (figurative speaking, I use them with my Speed Graphic and would not waste one like that).
You would think it would get in the way down there, but it does not seem to. The trick is to put it where it is between your wrists when you are typing. I did that by centering he cursor on the screen and then picking up the mouse and moving to to a point just below the "B" key. I find that instead of lifting my hand and moving it all the way to the end of the keyboard, I can just bend my arm at the elbow and my hand is on the mouse, bend it back and my hand is on the keyboard.
I will not know until I use it this way for awhile just how well I will wind up liking the idea. I figure I will have to give it at least a week because I keep moving my hand to the right end of the keyboard and then after hesitating bringing it back to the new mouse position. I do not think it would work for people who have their keyboard and mouse on a slide out tray, but for those of us who work on the table top it may be a better way to catch a mouse.