xorg update: keine HD-Auflösung mehr

[RalfGesellensetter]

Liebe Liste,

seit dem letzten Update von xorg (Debian sid/ux) erkennt der X-Server nicht mehr die maximale 
Auflösung von 1920x1200 - sie wird mir nicht mehr in systemsettings (KDE4) angeboten - 
laut xrandr nur noch analog, aber nicht über DVI (s.u.).

Wie bringe ich xorg modlines für DVI-0 bei? Dexconf kann es nicht von alleine, und
ohne xorg.conf geht's schon gar nicht.

Danke
Ralf

xrandr -q
Screen 0: minimum 320 x 200, current 1680 x 1050, maximum 1920 x 1920
VGA-0 connected (normal left inverted right x axis y axis)           
   1024x768       75.0 +   75.0     70.0     70.1     60.0     60.0  
   1920x1080      60.0 +   60.0                                      
   1920x1440      60.0                                               
   1856x1392      60.0                                               
   1792x1344      60.0                                               
   1920x1200      60.0                                               
   1600x1200      75.0     70.0     65.0     60.0     60.0           
   1680x1050      74.9     60.0     60.0                             
   1400x1050      75.0     72.0     60.0                             
   1280x1024      75.0     75.0     67.0     60.0     60.0           
   1440x900       75.0     59.9     60.0
   1280x960       75.0     72.0     60.0
   1368x768       60.0
   1152x900       66.0
   1280x800       60.0
   1152x864       75.0     75.0     60.0
   1280x768       60.0
   1024x600       60.0
   800x600        72.2     75.0     75.0     72.0     60.3     60.0     56.2     56.0
   768x576        75.0     72.0     60.0
   640x480        75.0     72.8     75.0     72.0     59.9     60.0
   720x400        70.1
DVI-0 connected 1680x1050+0+0 (normal left inverted right x axis y axis) 531mm x 298mm
   1024x768       75.0 +   70.1     60.0
   1680x1050      59.9*
   1280x1024      75.0     60.0
   1440x900       59.9
   1152x864       75.0
   800x600        72.2     75.0     60.3     56.2
   640x480        75.0     72.8     59.9
   720x400        70.1
S-video disconnected (normal left inverted right x axis y axis)


/etc/X11/xorg.conf:

# /etc/X11/xorg.conf (Xorg X Window System server configuration file)
#
# This file was generated by fll_xorgconfig, the F.U.L.L.S.T.O.R.Y.
# Xorg Configuration tool.
#
# Edit this file with caution, and see the xorg.conf(5) manual page.
# (Type "man xorg.conf" at the shell prompt.)
#
Section "ServerLayout"
        Identifier      "Xorg Configured"
        Screen          "Screen 0"
EndSection

#Section "ServerFlags"
#       Option          "AllowMouseOpenFail"    "true"
#       Option          "DontZap"               "false"
#EndSection

Section "Device"
        Identifier      "Device 0"
        Driver          "radeon"
        BoardName       "ATI Technologies Inc Radeon RV100 QY [Radeon 7000/VE]"
        BusID           "PCI:1:0:0"
EndSection

Section "Monitor"
        Identifier      "Monitor 0"
        ModelName       "Default Monitor"
        HorizSync       28-96
        VertRefresh     50-75
        # 640x350 @ 85.00 Hz (GTF) hsync: 31.28 kHz; pclk: 25.02 MHz
        Modeline "640x350"  25.02  640 656 720 800  350 351 354 368  -HSync +Vsync
        # 640x400 @ 85.00 Hz (GTF) hsync: 35.78 kHz; pclk: 29.20 MHz
        Modeline "640x400"  29.20  640 664 728 816  400 401 404 421  -HSync +Vsync
<----------------------------------- snip
...
<------------------------------------snap

        Modeline "1856x1392"  218.57  1856 1992 2192 2528  1392 1393 1396 1441  -HSync +Vsync
        # 1856x1392 @ 75.00 Hz (GTF) hsync: 108.97 kHz; pclk: 277.23 MHz
        Modeline "1856x1392"  277.23  1856 2000 2200 2544  1392 1393 1396 1453  -HSync +Vsync
        # 1920x1200 @ 60.00 Hz (GTF) hsync: 74.52 kHz; pclk: 193.16 MHz
        Modeline "1920x1200"  193.16  1920 2048 2256 2592  1200 1201 1204 1242  -HSync +Vsync
        # 1920x1440 @ 60.00 Hz (GTF) hsync: 89.40 kHz; pclk: 234.59 MHz
        Modeline "1920x1440"  234.59  1920 2064 2272 2624  1440 1441 1444 1490  -HSync +Vsync
        # 1920x1440 @ 75.00 Hz (GTF) hsync: 112.73 kHz; pclk: 297.59 MHz
        Modeline "1920x1440"  297.59  1920 2072 2280 2640  1440 1441 1444 1503  -HSync +Vsync
EndSection

Section "Screen"
        Identifier      "Screen 0"
        Monitor         "Monitor 0"
        DefaultColorDepth 24
        SubSection "Display"
                Depth   8
                Modes   "1024x768" "800x600" "640x480"
        EndSubSection
        SubSection "Display"
               Depth   15
                Modes   "1024x768" "800x600" "640x480"
        EndSubSection
        SubSection "Display"
                Depth   16
                Modes   "1024x768" "800x600" "640x480"
        EndSubSection
        SubSection "Display"
                Depth   24
                Modes   "1024x768" "800x600" "640x480"
        EndSubSection
EndSection

Section "Extensions"
        Option  "Composite"     "off"
EndSection