Is it possible to show key presses and mouse input visually?

Is there a way to visually show if keypresses and programmed mouse-buttons are properly sending their input?

Obviously, my keyboard is registering letter keys. But I can't tell whether my programmed mouse-buttons are properly sending their input, or if the problem is further down the chain with Windows' properly acting on the input. Likewise, sometimes my windows-key goes "out", but I'm not sure where in the chain of events it's failing.

From this blog post seems there are a number of scripts for AutoHotKey.

On Screen Keyboard displays a virtual keyboard and shows each keystroke as you type it. The button press visual is subtle, but it’s my favorite of the three.

and

ShowOff puts a plain white box in the corner of your screen and displays every keystroke and mouse click. You can change what keys to show, the font, colors and position as well as drag the window around.

and

osdHotkey is similar to ShowOff, displaying a window with colors that can be customized.

QiPress is a Windows plug-n-play utility I have written, with a variety of controls on what and how to display key presses on the screen.