xserver git(kdrive) and mouse

[l l]

It attachs,

I found that old Xfbdev(kdrive-cvs) also doesn't work if i give the
option (-mouse /dev/XXX),

$ Xfbdev -mouse /dev/usbmouse (this doesn't work)

But,

$ Xfbdev (this works fine)

Tell me why, Please.

TIA