When editing document properties in Inkscape, I have a long, hard-coded pre-determined list of random document sizes (see illustration below). I want to add to, and remove from, said list.
The issue has been mentioned a few times on launchpad (bug 171808 and 926209), and in the former a user says “This should be closed as fixed. It all is available in trunk.”
That was written in 2012, and it is not available in the current stable Inkscape (0.92.1 / r15371).
Question: How can I download, edit and compile the source code, so I can remove and add document sizes to my Inkscape?