Latitude E5430 and external VGA display specs

Hi,
I use a TV set connected to the VGA port of my Latitude E5430, with an Intel HD Graphics 4000 and Windows 7 SP1.

The TV set is recognized as "Monitor SONY TV" with a maximum resolution of 1280x768. However, I noticed the TV set must be turned on *before* the PC wakes from standby, or it is recognized as a generic external monitor and the display defaults to 800x600. That can be subsequently fixed only by using standby again or unplugging and reconnecting the VGA cable.

It looks as if the PC interrogates the VGA port to get the external display specs only once when it's powered up and there is no way to refresh the display specs again via software commands. Not really a big issue, but I'm curious to know if that's caused by firmware limitations, display driver or Windows 7.

I remember that a previous non-Dell PC with Windows XP worked perfectly and could detect the TV set model and resolution at any time.

Thank you and best regards,
/_urka