Windows – How to turn off the laptop monitor when using an external monitor

I have a Toshiba Laptop and I have searched all over the place for a solution to the following problem.

I use a Toshiba DynaDock to connect to an external monitor. I used to have Windows Vista, and while using that OS, whenever my external monitor was connected, the laptop monitor turned off completely. I recently upgraded to Windows 7 and that does not happen anymore. The screen stays blank, but the backlight is on.

Since it did work on Windows Vista, and since 7 is extremely similar to Windows Vista, I trust there is a way to set that up.

So my question is, is there a way to completely turn off the laptop monitor whilst using an external one, and whenever the external one is not connected, the laptop monitor works normally?

Also, I cannot use the power settings in 7, I have tried setting the monitor to turn off after a few mins, but it just dims and leaves the backlight on.