RegFromApp is a tool to record changes that are made to the registry.
It does not compare an archived state from before and after, instead it intercepts registry access and sees all changes as they happen.
It does not collect all registry changes made by any program.
Instead it either attaches to an already running process, or it can be told do
execute a command and attach to that process. In each case it collects only
the registry changes that made by that selected process,
thus it creates a relatively clean collection.
However I do sometimes see entries that I cannot understand,
especially when running it in Windows 7.
For example in Windows 7 it claims that the setup.exe from the Firefox installer
creates the key
The output can be saved in reg-files of either format 4 or 5.
The program can be used either by clicking in its GUI, or fully automated from the command line.
My use of RegFromApp is to fully automate the process to create Firefox.msi with WiX.
RegFromApp does not need to be installed, but it must be run with admin rights.
In my experience it doesn't yet really like Windows 7, but it can be run when Win7 is told to execute it in compatibility mode of XP.
More info can be found on www.nirsoft.net/utils/reg_file_from_application.html.
There are two separate versions for 32 and 64 bit Windows.