sparc cg3 1152x900 display abnormal

when I use -vga cg3 -g 1152x900 with qemu-system-sparc, the display is abnormal
I had try qemu-2.1.0 on win2003 with openBIOS or OBP
    qemu-system-sparc.exe -vga cg3 -g 1152x900
or
    qemu-system-sparc.exe -vga cg3 -g 1152x900 -bios ss5.bin

I also try qemu-2.0.2 on debian 6.0.1a i686 on VirtualBox host win2003
with same command, in vnc view, the display is same as on win2003.

If I don't use -g 1152x900 parameter, everything is OK, sunOS 4.1.4 work well.