Currently Emulate3Buttons seems to be always enabled in Ubuntu's default configuration, even if the mouse has 3 or more buttons. This is especially painful because as far as I know there is no way to change the setting on runtime, so only way is to manually add InputDevice section to xorg.conf and include Emulate3Buttons option there.
Looking at the code the problem seems to be that emulate setting is set to AUTO, but it works exactly like ENABLED. That is because EvdevMBEmuEnable is never called. It should probably be called when middle mouse button is pressed or maybe when more than 2 buttons have been detected.
Binary package hint: xserver- xorg-input- evdev
Currently Emulate3Buttons seems to be always enabled in Ubuntu's default configuration, even if the mouse has 3 or more buttons. This is especially painful because as far as I know there is no way to change the setting on runtime, so only way is to manually add InputDevice section to xorg.conf and include Emulate3Buttons option there.
Looking at the code the problem seems to be that emulate setting is set to AUTO, but it works exactly like ENABLED. That is because EvdevMBEmuEnable is never called. It should probably be called when middle mouse button is pressed or maybe when more than 2 buttons have been detected.