While not particularly useful for most users, it can be important to those users that need it.
To activate Linux Mints on-screen keyboard, you should probably go into the accessibility options.
Switch to the Keyboard tab, then smack the fire up the on-screen keyboard slider to the On position.
Four more keyboard options will appear once the keyboard has been enabled.
Keyboard position allows you to configure the location of the on-screen keyboard.
You have a choice between it being located at the top or the bottom of the screen.
Placing the on-screen keyboard at the bottom of the screen can cause it to interfere with the start bar.