The play pointer and stop square indicators are sufficient for VNA modes, DTF and spectrum analysis because you can easily see the device is operating by the sweeping action of the display.
This is not true for the AF and RF generator functions. I have been trapped a number of times looking for the level I have set up on the KC901V on another instrument , checking cables for faults when I did not get a result only to find the generator output is off as per the first picture below as indicated by the small square stop indicator.
and the output is on as per the small pointing forward arrow play indication in this next picture. There is nothing else to indicate whether the generator is working or not.
I suggest that when the output is off that the output display level be made to pulse on and off at the rate of about one pulse per second to warn the user that the level is not being supplied. This is the same as used in many VCRs and DVD players in the past when they were in pause mode which is what the mode effectively is.
This would be particularly useful in the field because there are many other factors which could lead to you not seeing a signal at the receiver or device you are testing.
Modify the AF and RF generator programs to pulse the output level indication when the output is off including when you are adjusting the level and it is highlighted.