Feature request: arrowkey increments with math

In sidebearing text boxes I appreciate being able to arrow up and down to change the value by 1 (or with shift, by 10).
It would be useful if the same trick worked with “arithmetic” sidebearing values.
That is, if given a LSB value “=n+12”, shift-up would change it to “=n+22”.

Hi everyone,

I was going to request this feature too. I find it very useful. I see the original message is from 2013, is there any news in this respect?