Want to stop workplace, school, and other senseless shootings? Allow concealed carry everywhere!
Do you speed in your car? I bet you do....well that's against the law. You're just rolling the dice that you won't get caught. Same rules apply for guns. Just because there is a sign on a door stating no guns, that's not going to stop some crazy psychopath from entering a building and shooting it up. You can create laws banning and taking away all kinds of stuff, but it's not going to stop bad people from doing bad things.
If a bad guy things you might be armed, then maybe he'll think twice from entering a building and getting taken out by a concealed carry holder.
Of course, most of the psycho's out there - they have some major mental issues, and unfortunately, our government buracracies are not taking care of the problem and vetting the people they should be well enough. Just too much government. Make smaller government, and we'll have smaller problems. But that's another post in itself.