pivot: operation for date values

I have a pivot table and some columns have date values.

I tried using max and min but they don’t work. I looked at the code for min and max and saw that they only support numbers.
So I created custom min and max operations (and total operations) and used addOperation() and addTotalOperation() to let the pivot widget know about them.

But that still did not work.

I looked again in pivot_debug.js and found that pivot supports operations only on numeric column values.
There is code there that checks if the value is a number:

if (!isNaN(parseFloat(value)))

Is this intentional?
It would be very useful for us to be able to have date (or other data types) and allow them to be aggregated in a way that makes sense to the data type.

For dates, it’s perfectly logical to look for min and max dates.

Is this a bug?

Thanks in advance…