Add "base" key labels (optionally)

[Evgeny]

It would be great if (at least in print mode) there were an additional option that retained the labels of the 'base' key layer in other layers so that it'd be easier to see where that modified key is exactly
For example, if we have ^d→≈ it would be nice to have on the ^ keyboard layer instead of only 1 label (currently):
≈
have two labels:
b≈
where b could be in light grey in the top left corner not to be confused with the main symbol ≈

[eduo]

I assume this request is for something like the image below. I came here to ask for this as well. Specially for printing it would be very useful.

(image taken from https://www.farah.cl/ )