| Know what to leave behind |
Having a complete and efficient uninstall program is great, but remember not to go over the top; there are some things you should leave behind.
Often the tendency is to assume that you should remove all the files that you installed as part of your application, and remove all trace of your program. But there are certain files that you should leave behind after uninstalling. System files, such as fonts, and shared components still in use should be left, as should any user created data files. If you installed any operating system updates such as service packs, they should also stay. You should also make sure to clean up any registry entries you have created, but not before you ask the user if they’d like to keep them. See Give the user a chance to be remembered.
One way to track the use of shared components is to reference count the consumers of a component, but this is often troublesome and can be undermined by other install programs that don’t reference count. By using the Microsoft® Windows® Installer Service to author your setup programs, the system takes care of tasks like component reference counting, freeing you to concentrate on other issues and ultimately resulting in a better install/uninstall experience for the user.