Preview Tab

Not without source code changes - Gmoccapy has no user access to it's code.

Unfortunately I can not understand what you want to do in detail.

Can you please post two screenshots, showing one and the other notebook tab you want to change?
It might be a good idea to introduce Hal pin for that purpose. Would not be too much work.

Norbert

P.S, I was already thinking about opening all gmoccapy functions to be activated from an external source, but I did not find a good solution yet. So if someone has an ides how to archive an external command to be forwarded to gmoccapy, please let me know.

He wants to control tab selection prom a separate program.
There have been several ways this has been done to date.
I added X11 client messages to AXIS to let gladevcp program know if the glade panel was showing for Andy.
AXIS has axis-remote for some external control.
HAL pins are a quick and dirty way to do it.
Ultimately I think opening your code to user modifications is the best way (ie something like handler file), so the user can decide the best technique.

Saying that, in the long run maybe I should add a zeroQM module into Qtvcp so inter program communication is easier.

It would be ultimately best if linuxcnc it's self utilized an easy to use interprogram communication system. NML is what linuxcnc uses and it's not easy to use or expand. Machinekit chose zeroQM but IFAIK they didn't get it beyond HAL communication.