I can not interrogate middle mouse buttons. Value always remains false=0.
SetErrorMode(2)
SetSyncRate(5,0)
while GetRawKeyPressed(27)=0
Print("Press Mouse Buttons")
Print("")
Print("Left "+Str(GetRawMouseLeftPressed())+Str(GetRawMouseLeftState())+Str(GetRawMouseLeftReleased())+" OK")
Print("Middle "+Str(GetRawMouseMiddlePressed())+Str(GetRawMouseMiddleState())+Str(GetRawMouseMiddleReleased())+" Indiscernible")
Print("Right "+Str(GetRawMouseRightPressed())+Str(GetRawMouseRightState())+Str(GetRawMouseRightReleased())+" OK")
Sync()
EndWhile
AGK2: AppGameKit IDE 2017.04.24
System: Lubuntu LXDE (based on Ubuntu 16.10)
Kernel: Linux 4.8.0-46-generic (x86_64)
Processor: Intel Core i7-4790K @ 4.00 GHz
Mainboard: Asus Maximus VII Gene
Grafik: OnBoard