Problem with xserver and framebuffer

[José Salavert Torres <josator@telefonica.net>]

The screen doesn't fill the whole monitor. It moves around when the
pointer is near to the edge.

I don't know why this happens, because server is set to 1024x768 in all
modes, here is my XF86config.

This has happened when I've updated form 4.2.1-3 to 4.2.1-4

### BEGIN DEBCONF SECTION
# XF86Config-4 (XFree86 server configuration file) generated by dexconf, the
# Debian X Configuration tool, using values from the debconf database.
#
# Edit this file with caution, and see the XF86Config-4 manual page.
# (Type "man XF86Config-4" at the shell prompt.)
#
# If you want your changes to this file preserved by dexconf, only make changes
# before the "### BEGIN DEBCONF SECTION" line above, and/or after the
# "### END DEBCONF SECTION" line below.
#
# To change things within the debconf section, run the command:
#   dpkg-reconfigure xserver-xfree86
# as root.  Also see "How do I add custom sections to a dexconf-generated
# XF86Config or XF86Config-4 file?" in /usr/share/doc/xfree86-common/FAQ.gz.

Section "Files"
	FontPath	"unix/:7100"			# local font server
	# if the local font server has problems, we can fall back on these
	FontPath	"/usr/lib/X11/fonts/misc"
	FontPath	"/usr/lib/X11/fonts/cyrillic"
	FontPath	"/usr/lib/X11/fonts/100dpi/:unscaled"
	FontPath	"/usr/lib/X11/fonts/75dpi/:unscaled"
	FontPath	"/usr/lib/X11/fonts/Type1"
	FontPath	"/usr/lib/X11/fonts/Speedo"
	FontPath	"/usr/lib/X11/fonts/100dpi"
	FontPath	"/usr/lib/X11/fonts/75dpi"
EndSection

Section "Module"
	Load	"GLcore"
	Load	"bitmap"
	Load	"dbe"
	Load	"ddc"
	Load	"dri"
	Load	"extmod"
	Load	"glx"
	Load	"int10"
	Load	"record"
	Load	"speedo"
	Load	"type1"
	Load	"vbe"
	Load	"xtt"
EndSection

Section "InputDevice"
	Identifier	"Generic Keyboard"
	Driver		"keyboard"
	Option		"CoreKeyboard"
	Option		"XkbRules"	"xfree86"
	Option		"XkbModel"	"pc104"
	Option		"XkbLayout"	"es"
EndSection

Section "InputDevice"
	Identifier	"Configured Mouse"
	Driver		"mouse"
	Option		"CorePointer"
	Option		"Device"		"/dev/input/mice"
	Option		"Protocol"		"ImPS/2"
	Option		"Emulate3Buttons"	"true"
EndSection

Section "Device"
	Identifier	"Nvidia GeForce2 MX400"
	Driver		"fbdev"
	BusID		"PCI:0:16:0"
	VideoRam	32768
	Option		"UseFBDev"		"true"
EndSection

Section "Monitor"
	Identifier	"Apple Studio Display 15'"
	HorizSync	30-60
	VertRefresh	50-75
	Option		"DPMS"
EndSection

Section "Screen"
	Identifier	"Default Screen"
	Device		"Nvidia GeForce2 MX400"
	Monitor		"Apple Studio Display 15'"
	DefaultDepth	24

	SubSection "Display"
		Depth		8
		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 "ServerLayout"
	Identifier	"Default Layout"
	Screen		"Default Screen"
	InputDevice	"Generic Keyboard"
	InputDevice	"Configured Mouse"
EndSection

Section "DRI"
	Mode	0666
EndSection

### END DEBCONF SECTION