How are Budgets Implemented in GNU Cash

[Matt Graham]

I would like to contribute to GNUCash, and get into the development side of the house.

I figure that a (relatively) quick and easy contribution (that will also help me personally) is for me to create a patch to correct the bug where budgeted expenses don’t show up in the summary section at the bottom of the screen (https://bugzilla.gnome.org/show_bug.cgi?id=742352).

My problem is that I cannot find (from the documentation) where the budget side of code is implemented within GNU Cash (even after much Googling). Can anyone steer me towards somewhere to look for more information about how Budgets are implemented?

Thanks,

Matt