How to set G-code line highlighting?

Hi guys, I'm running into a problem that I can't escape.
How do I set G-code line highlighting? When I use my own interface or other configuration interface, the running highlight of G-code lines cannot be controlled. Especially my custom M codes (M100-M199) and remapping codes, these are not highlighted, where should I go to see this? Or how to control the highlighting of G code lines?
Thank you, I hope you can give me some advice.

I bet there is not much you can do without a lot of internal work.
The screens use a linuxcnc status message to tell them what line linuxcnc is on.
Internally linuxcnc doesn't always create a motion message for each line of Gcode.
It will combine some.

I am not sure how remap and custom code is handled internally, but I would not be surprised if they don't keep track of gcode line.
There are also a 'state Tag' mechanism for keeping track of current state.
I must admit my understanding of this process is hazy.

OK, thanks cmorley
I'll try new ways, what is this "state  tag " mechanism? I may not quite understand. . .

State tags were introduced to fix the problem for say M code being reported out of sync with the current state, This was because the reported state was the 'interpreted' state not the current state. The interpreter often runs ahead of the current motion.

my take is that gcode is read and tokenised into a buffer and then the gcode is thrown away. State tags attaches the interpreter state to that tokenised motion segment at the time of reading so it can be checked in real time when it is eventually executed. But the state tags structure is not easilly exposed. I would like to see the data  published on motion pins.