How to best show interface messages?

I’m developing a game that has a tutorial level. This tutorial level shows you an informative message when you collide with a trigger box. The game controls are:

  • typical WASD for movement
  • SPACE for jump
  • and mouse for camera yaw.

I want the game to stop any input (not WASD movement, not jumping and not yaw from the mouse). To do that, I thought about two ways:

  1. Pause the game and show a widget screen over it and then un-pause it.
  2. Disable any input movement from user.

Right now I’m using the second method like this:

After that, when I press the OK button on the message screen, I revert the Set Ignore Move Input and the Set Ignore Look Input. But when I do so, my mouse is in the same position as the accept button is, and I recover the control in that place. When you push more than one button, it gets annoying :S

One solution would be to set the mouse position in the screen center, so, my first question would be:
Is there any way in which I can set the mouse position to the center of the screen?

Since now I tried this:

but I don’t know what to to with that Set Mouse Position

So my question will be: I know there are games that allow you to insert messages, stop gameplay, and then give control back to the user. Is this the correct way to do so?