ARGH!

Supervisor: I need you to take over development of X.
Me: Sure. What do you want me to do?
S: Oh, nothing for now. Focus on Y and Z (both long term goals) first.

(a month later)

Me: Ok, whoever wrote this in the first place didn't plan for any changes - in fact, most of the code is either broken or held together with spit and string. Here is a list of things that don't work.
S: Ok, but keep forcusing on Y and Z. Also, we don't have funding for X any more, so we're putting it on hold.

(2 months later)

S: WHERE ARE THE FIXES FOR THE BUGS YOU FOUND? THIS IS DUE IN 2 WEEKS!
Me: ... Ok, I'll get on it.

(next day)

Me: Ok, here is a demo of the things I changed to fix (half the bugs on the list + others that I found while coding)
S: OMG WHAT ARE YOU DOING, YOU SHOULD ONLY FIX THE PROBLEMS, NOT ADD ANY FEATURES.
Me: ... These ARE the bug fixes.
S: NO NO DON'T CHANGE ANYTHING UNTIL I APPROVE IT, WE DON'T HAVE FUNDING FOR IT! JUST FIX THE BUGS.
Me: (just shoot me now)

Repeat after me:

A master document is not a tree. It can be viewed as a tree, but when an element has more than one parent, it is not a tree, no matter how badly you wan to call it one. NOT. A. TREE.

Also, displaying the content of a set of elements is not coupled to how said elements are stored. That's called designing before implementing, and using wrappers for displaying.