I'm struggling to find documentation on how the stateSaver/savedState Dictionary works for the Windows Installer, in the Install and UnInstall overrides, can someone help.

In my installers CustomAction I've been writing to registry entries, each time I do I add some of it's detail to the stateSaver. I had presumed this was taken into account when uninstalling but how?

I think the stateSaver Dictionary is written to file when you install, and on uninstall the content of that file, .InstallState is read and used to install the entries it finds.

How does the InstallState IDictionary work?

For registry entries in particular, do you add the Value in the InstallState as the full path the the registry entry? and at Uninstall will it install that registry key with any explicit code by the developer?

I'm creating a registry key with subkeys and values in my Custom Action, but it doesn't get uninstalled. I've added the key name as the Value in the InstallState but it doesn't get deleted. I've also tried deleting it programmatically in the UnInstall override but it fails, permissions I think.

My issue is some registry entries remain after uninstall, I don't know why and my lack of understanding of how the Dictionary works is not helping.

Here's an example of what the Install is doing

//add the root key of what I'm about to create to the InstallState.

RegistryKey expressionEvalKeyRoot = hKeyClassesRootCLSID.OpenSubKey("{" + guidString + "}");

stateSaver.Add("ExpressionEvaluator"+guidString, expressionEvalKeyRoot.ToString() );//will be deleted in the uninstall

RegistryKey expressionEvaluatorVersionKey = expressionEvaluatorKey.CreateSubKey(packageVersion);
stateSaver.Add("MyKey", expressionEvaluatorKey.OpenSubKey(packageVersion).ToString());

I would have thought that the base.Uninstall(savedState) would have uninstalled the key, both the root and the actual subkey, but it doesn't.

I also tried using DeleteSubKeyTree to delete the key from the root

RegistryKey hKeyClassesRootCLSID = Registry.ClassesRoot.OpenSubKey("CLSID") as RegistryKey;

hKeyClassesRootCLSID.DeleteSubKeyTree(savedState["MyKey"].ToString()); 

but I get an exception, permissions. I shouldn't need to do this anyway.