Is it possible to reload (Windows) environment variables?
If you set an environment variable in the registry (or via the System Properties > Advanced > Environment Variables UI), it will be global and persistent for every process launched from the top level context created after the variable was set.  Shells and contexts initialized before your change will not pick up those changes unless you explicitly merge the values from the registry with the existing values in that context though.  Each context inherits the environment of its parent, but after that point, changes to the parent or child environments do not propagate in either direction.  Contexts created at the top level get their environment from the registry.
Exactly what it says. I can set per-user environment variables, either from Windows > type "Path", or using RegEdit, or even from a Python script.
But if I run an application (e.g. from Launchy, or launch it from Chrome), it won't pick up the new variables. I've got to start a new cmd or Windows Explorer (I think) to get the new values.
Now, obviously I can set them on a per-use basis, but I want to set them globally for my account, and also for whatever process I happen to be using at the time. Is this possible? And is it possible (or easier) to do from a Python script?