Setting DisplaySize in dexconf-generated XF86Config ?

["Nikita V. Youshchenko" <yoush@cs.msu.su>]

Some experiments show that to get best results with OpenOffice.org (and 
probably other packages), X server's DPI value should be set to real 
monitor DPI.

XFree86 seems to have an excellent way to do that.
In XF86Config-4, in section "Monitor", one can write
	DisplaySize     320 240
and specify physical monitor dimensions that way.
Using that information, X server will calculate correct DPI value.

Some modern software (xft/fontconfig-based) uses Xft.dpi resource; this 
may be set by adding something like

dpi=`xdpyinfo |
       awk '/resolution/ {split($2, x, "x"); print(int((x[1]+x[2])/2))}'`
echo "Xft.dpi: $dpi" | xrdb -merge

to /etc/X11/Xsession.d/95dpi

Perhaps a question about physical monitor dimensions should be added to 
xserver-xfree86 debconf templates. It should have pre-defined values for 
common situations (such as 320x240 mm for 17'' monitors), and allow user 
to enter explicit values if he wishes (or not to set DisplaySize at all).

I believe it's much better than just assume 100dpi by default (as it is 
now).