You are right Dave R...
It is an issue for me, an issue for beginner and intermediate user, and may also be an issue for some professional user. My point is to prevent such issue so that you dont have to train your hands and mouse cursor. I thought of before someone could make such plugin. And maybe you dont need such plugin if it is in the menu when you right click the mouse; locking a point, a line, axes[X,Y,Z], or a plane[face].