Now that I've finally implemented the M3/M4/M5 codes, I've stumbled in a new problem.

It looks like these command when invoked within a G-code program, are executed EARLIER than expected. At least 1 step before.

e.g. if I wrote something like:

1) G1 ......
2) G1 ......
3) M3
4) G1 ......

and hit the "run" button, the command n. 3) is actually executed BEFORE command 2)

Everything works as expected if I run it step by step instead, hence I suspect that's something having to do with the lookahead.

This is a dangerous problem... imagine one inserted an M5 (stop spindle) after the last machining step (like I did) and when running the program the spindle stopped rotating while the endmill was still moving inside the workpiece!!!!

EC