Lehmer's profile - activity

In my code, I have a window which shows me camera processed images, and I need it notifies me when some conditions happen. I can write on the window a message... but I'd like to have this message only for 5 seconds, then dissapear, and be empty until new message appear. If not, the messages superimpose over the others, and is imposible to read them.

Is any way?

Thanks a lot!