ResHacker (correct name: Resource Hacker) is just another tool/utility program to change some things in another file.
More precisely changing/editing resources in a file (can be an exe, dll, or any other file which can hold resources). So, it isn't related to messenger either. Messenger is just a program which happens to have resources, like oh-so-many other programs.
It is just like using your Photo Editor to fix that red eye in that nice photograph. Afterwards you don't need your Photo Editor to view that photo. And the Photo Editor software is also installed like any other normal program, once, in its own directory.
BTW: ResHacker doesn't really need to be 'installed' (like bigger programs, like Messenger itself for example). You can just copy the program into any folder you want and start using it from there.
quote:
from the official site, first paragraph:
What is Resource Hacker?
Resource Hacker is a freeware utility to view, modify, rename, add, delete and extract resources in 32bit Windows executables and resource files (*.res). It incorporates an internal resource script compiler and decompiler and works on Win95, Win98, WinME, WinNT, Win2000 and WinXP operating systems.
Tip: read the tutorial links listed on the site...
reshacker.ini holds the settings and options for ResHacker.
INI files are typically used when not much settings needs to be stored and when the author of the program has choosen not to use the Windows Registry to store stuff.
reshacker.gid is an index file created the first time you used the search function in ResHacker's Windows Help file.
GID files are always created when you use the search feature of a particular Windows Help File. They hold the index of the Help file and are used to speed up searching.