It occurred to me that Luc DESFOSSES wrote in gmane.os.netbsd.general:
> Thanks for your answer, 
>
> The screen is a 1400*1050 tft
> I'm searching all over the net to find the 2 value... :)

You probably won't need them. The autoconfig routine probably mis-matches
your TFT panel, and apperently selects a default resolution which your
panel doesn't quite understand - it likely selects a "normal" 4:3 resolution,
instead of your widescreen resolution. I've seen it happen before.

What you could do is run

XFree86 -configure

like you did before, and edit the generated XF86Config.new file.
What you should do is modify the "screen" section, and add a line
reading 

Modes	    "1400x1050"

to the appropriate subsection, so that it gets to read

	Subsection  "Display"
		Viewport    0 0
		Modes	    "1400x1050"
		Depth	    8
	EndSubSection.

I don't know what default depth xf86cfg expects (Probably 8bpp), but I would
add such a Modes line to every "Display" subsction, just in case.
	
After that, run

xf86cfg -xf86config ~/XF86Config.new

If that doesn't help, I think you should post more information. Especially
the contents of /var/log/XFree86.?.log, as noone will be able to help you
any more without more details.
-- 
    Martijn van Buul - pino@dohd.org - http://www.stack.nl/~martijnb/
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