That's relevant to those who are infected with software, not to this forum specifically. What happens here is that you are randomly logged out, and the keystrokes on this site are logged.
Since I noticed this a couple weeks ago when I was randomly logged out, I simply typed the password in a different place and pasted my password into the forums. I then changed my password and ran a pre-boot scan. A couple days later, I stopped being logged out randomly.
Users may combine an on-screen keyboard with typing it into a different place than the forums if they are certain they are not infected.