Normal widescreen PC panels have an 1.6 AR (1920x1200, 1680x1050, 1280x800). Anything else is rarely used so, afaik if you design your game to run at 1.6 you have covered almost all widescreen monitors and most 4:3 monitors (since 1280x800 is available to most of them).
Yes odnorf, I thought so too and this is why I choose 1280X800, but this does not work.
As Mnemonic confirmed, the only way to have fullscreen, is the game resolution to be in the list seen by the DX utility he posted.
So, running this to different systems (nvidia, ati) gives different lists. But there was nowhere the 1280X800.
For nvidia the closest is 1600X900, for ati is 1280X720, so I can't have fullscreen.
(for nvidia I managed to "have" this 1280X800 and play at fullscreen by manually add it to the driver, but this is not a global solution)
Given the facts:
1. I can't know the list of valid resolutions (except my own system using the DX utility),
2. This list depends on the video card / monitor combination,
How can I decide a proper average game resolution?
This is a mess
(may be I should ask about this in an other post alone)
Spyros