Windows binary package uninstaller should cleanup plugin cache data left in the Windows Registry

Qt puts plugin information into the Windows Registry. Currently this information is left behind when Qt is uninstalled.

The information contains the Qt installation directory, for example:

HKEY_CURRENT_USER\Software\Trolltech\OrganizationDefaults\Qt Factory Cache 4.7\com.trolltech.Qt.QImageIOHandlerFactoryInterface:\C:\work\packages\Qt4.7.1-MSVC2005\plugins
HKEY_CURRENT_USER\Software\Trolltech\OrganizationDefaults\Qt Plugin Cache 4.7.false\C:\work\packages\Qt4.7.1-MSVC2005\plugins\imageformats

Since the uninstaller knows where Qt was installed it can remove anything that matches those paths.

Perhaps the best way to handle this is to add a small utility .exe to Qt's bin directory. That way, the binary package uninstaller could invoke it at the beginning of the uninstall process, and the user could invoke it before manually deleting a source package's directory tree.