Emulate3Buttons not honored

[K Vanw]

I'm trying to get my "ORtek Wireless Touchpad keyboard" to emulate 3
buttons. If I use xinput to set the "Evdev Middle Button Emulation" to
true, it works fine. But I can't get X to set that property from
x.config. I have this file (55-3button.conf) in my x.config.d/ folder:

Section "InputClass"
 Identifier "Middle button emulation class"
 MatchIsPointer "on"
 MatchProduct "ORtek Wireless Touchpad Keyboard"
 Option "Emulate3Buttons" "on"
 Option "Emulate3Timeout" "51"
EndSection

The relevant lines in Xorg.0.log are:

[104142.299] (**) ORtek Wireless Touchpad Keyboard: Applying
InputClass "Middle button emulation class"
[104142.300] (--) ORtek Wireless Touchpad Keyboard: Found 3 mouse buttons
[104142.300] (--) ORtek Wireless Touchpad Keyboard: Found scroll wheel(s)
[104142.300] (--) ORtek Wireless Touchpad Keyboard: Found relative axes
[104142.300] (--) ORtek Wireless Touchpad Keyboard: Found x and y relative axes
[104142.300] (--) ORtek Wireless Touchpad Keyboard: Found keys
[104142.300] (II) ORtek Wireless Touchpad Keyboard: Configuring as mouse
[104142.300] (II) ORtek Wireless Touchpad Keyboard: Configuring as keyboard
[104142.300] (II) ORtek Wireless Touchpad Keyboard: Adding scrollwheel support
[104142.300] (**) Option "Emulate3Buttons" "on"
[104142.300] (**) Option "Emulate3Timeout" "51"
[104142.300] (**) ORtek Wireless Touchpad Keyboard: YAxisMapping:
buttons 4 and 5
[104142.300] (**) ORtek Wireless Touchpad Keyboard:
EmulateWheelButton: 4, EmulateWheelInertia: 10, EmulateWheelTimeout:
200

Note that X reports that it 'Found 3 mouse buttons', but in fact there
are only 2 real buttons. After X starts, xinput reports:

# xinput list-props 'pointer:ORtek Wireless Touchpad Keyboard'
Device 'ORtek Wireless Touchpad Keyboard':
Device Enabled (134): 1
Coordinate Transformation Matrix (136): 1.000000, 0.000000, 0.000000,
0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000
Device Accel Profile (261): 0
Device Accel Constant Deceleration (262): 1.000000
Device Accel Adaptive Deceleration (263): 1.000000
Device Accel Velocity Scaling (264): 10.000000
Device Product ID (253): 1444, 4096
Device Node (254): "/dev/input/event5"
Evdev Axis Inversion (265): 0, 0
Evdev Axes Swap (267): 0
Axis Labels (268): "Rel X" (144), "Rel Y" (145)
Button Labels (269): "Button Left" (137), "Button Middle" (138),
"Button Right" (139), "Button Wheel Up" (140), "Button Wheel Down"
(141), "Button Horiz Wheel Left" (142), "Button Horiz Wheel Right"
(143)
Evdev Middle Button Emulation (270): 0
Evdev Middle Button Timeout (271): 51
Evdev Wheel Emulation (272): 0
Evdev Wheel Emulation Axes (273): 0, 0, 4, 5
Evdev Wheel Emulation Inertia (274): 10
Evdev Wheel Emulation Timeout (275): 200
Evdev Wheel Emulation Button (276): 4
Evdev Drag Lock Buttons (277): 0

As you can see, the Middle Button Emulation is not set. but "xinput
set-prop 10 270 1" will set it correctly. So how do I get this set via
an xorg.conf.d file?

Thanks,

Kevin