I'm using Vice 3.6.0 r41412 on Linux Mint 19.3 Tricia Xfce edition with Nvidia Graphics Card GeForce GTX 1050. I have compiled and installed the GTK3 version of Vice.
I load the game Star Trek The Rebel Universe which is a mouse driven game.
I go to Preferences>Settings>Input devices>Control port
and set the Control port #2 to Mouse (1351)
I press [Alt] + m to grub the mouse pointer. When I resume the game the mouse pointer moves only when I click the right mouse button and it goes only in the upward direction. No other movement of the mouse affects the mouse pointer.
try using port1
I've tried to use port #1 but in this case there is no movement of the mouse pointer at all, no matter what I click or move.
The reason the mouse does not work correctly is because it is a joystick game, please change control port 2 to use a joystick and then change joystick port 2 to use numpad or keyset 1, or keyset 2, or a host joystick if you have it.
My bad. You're right it is a joystick only game :(