Event Listener for Stationary Camera

My colleagues and I are working on some Python code which includes a heads up display containing information about the model.

We’d like for the HUD to only appear when the user is not moving the viewport around, or, in other words, when the current viewport camera is stationary for more than, say, a couple seconds.

Is there a way to listen for an event like a stationary camera?

Better solution: Run your script as a command with an alias assigned to it. If the user wishes to display the model data, he / she can toggle data on / off via a keyboard shortcut to the command.