From: Alan Chen <Digikata@...>
Date: 2005-07-19T04:15:55+09:00
Subject: Re: windows - How to propagate environment variables to the system

To get the registry settings having to do with environment to stick
without rebooting you also need to broadcast a message to notify
processes of the change. Here's my revant code snippet: (Watch the urls
in my comments. they may wrap badly)

# broadcast a settings change
# http://support.microsoft.com/?kbid=104011 the exact issue
# WM_SETTINGCHANGE info
#
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/sysinfo/base/wm_settingchange.asp
# SendMessage info
#
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/winui/winui/windowsuserinterface/windowing/messagesandmessagequeues/messagesandmessagequeuesreference/messagesandmessagequeuesfunctions/sendmessage.asp

require 'Win32API'
SendMessage = Win32API.new("user32", "SendMessage", ['L', 'L', 'P',
'P'], 'L')
HWND_BROADCAST   = 0xffff
WM_SETTINGCHANGE = 0x001A
puts SendMessage.Call(HWND_BROADCAST,WM_SETTINGCHANGE, 0,
"Environment")

It took me a week of head-scratching to figure out that registry.rb
made the right changes, but they weren't being
accepted quite correctly - especially when you want to use other Env
variables in your definition. e.g. SRCTREE = %HOME%/blah/blah

HTH,
- alan