NGUI resorting depths

[Tatanan]

Does NGUI re-sort depths in some cases (like gaps between depths or negative depths?
Actually, it's not a question, I am seeing that indeed NGUI re-sort depths in some cases, so the question is
Why?
and
When?

Thank you.

[ArenMook]

It's just an integer value. The list is sorted by it.

[Tatanan]

I think I didn't make correctly the question.
I know they are integers.
Let's suppose my depths are:
-2
-1
0
2
3
Then, when I click on "Play", those integer becomes 0, 1, 2, 3 and 4, so I can't trust on these values, for example, for adding my own depth programatically.
Is it clearer now the question?

[ArenMook]

Depth values don't change unless you change them. Your -2 -1 0 2 3 will remain as such. Nothing will change them to 0 1 2 3 4. Only normalizing depths or using ALT+SHIFT+= (or minus) will place them in order like that.

[Tatanan]

For some reason the values on my scene do change. I don't know why and I haven't writen any code for doing this.
Maybe I'm using NGUI class which does it internally, I don't know.
Don't worry then, it's not a real problem.
Thank you.