What this quick and dirty shell script does is:

• start Gromit-MPX
• add two new XI2 pointer-keyboard pairs
• simultaneously do an action with both of them
• remove them again

Launch with ./test-tool-multi-user.sh <path to gromit-mpx> <tool>, e.g.

./test-tool-multi-user.sh ../build/gromit-mpx PEN

or

./test-tool-multi-user.sh ../build/gromit-mpx RECT

or any other tool.