rename tree item

[h4ever]

Hi, I use program which source code is published but it has one bug that when I copy/paste item in tree it produces some weird characters on end of the string. This looks like author changes the title of item so does not keep the title same. I need to find the code which copies the tree item but don't know what should I look for. It is huge project so I need some tip, what functions, variables or words should I look for. Is there some function to rename the tree item?