Given that useless, unproductive gov't spending is called "investment", replacing your windows is just another "investment" too.
(It's be cheaper to buy a few rounds to replace the expended "investments".)
In mivogo's scenario, wealth has been depleted to get back to the original state. In other words, resources are consumed , but in the end we end up in the original condition of intact windows (Until the vandals decide to strike again, that is).
On the other hand, if the window owners 'invested' in shot guns for the same cost as replacing the windows, we attain a state where we now have both windows and shot guns, so we have more wealth, and less brazen vandals. A win-win all around, if you ask me.