Please add a preference to lock the entire keyboard, and also the trackpad for laptops as well as mouse buttons if possible, except for one user-specified key. If the trackpad or a mouse button is pressed while cleaning it can trigger unwanted actions just like the keys.
Currently, the modifier keys (fn, control, option, command, shift, etc.) also remain unlocked, and in my case I need to use a screensaver outputting to a projector w/out having unwanted key strokes interfere w/ the video. Your tool works great to prevent the character keys from interrupting the screensaver, but the other keys still do. There may be other uses for this as well. I realize you can’t lock all keys b/c then there’s no way to access the app again :]
My suggestion would be to add a preference to the effect of:
• Lock entire keyboard, trackpad, and mouse buttons except for one specified key: [ esc ]. (“Escape” is the user-selected key in this example.)