I dont know if this has been already been mentioned, but this is a very handy tool to assist in modifying themes.
Basically, it lets you search multiple files (in this case, *.xml’s) for instances of text,phrases,code etc.
It installs as a ‘shell extension in Windows’ so you just 'right click… PRGrep.
eg. I want to find where the png graphic file “setup_logo.png” is referenced in all the wdtv live hub xml files.
Here is the search results:
Note: this program does not support right click paste on the mouse… copy the filename and in the “Containing” field hold CTRL+V to paste it … then hit “Enter” button on your keyboard.
This has been an invaluable tool in my latest work in modifiying setup/settings xmls.
(Have been using it for a few years now)
P.S. It’s Freeware 
