Confirmed; looks like the same-domain issue was fixed — maybe with the latest Steam update, considering it affected most games.
If you're using this plugin just for the same-domain fixes, you'll probably want to uninstall it after some time in case people are not up-to-date for some reason (if they ignore Steam's update nags, for example).
If you're using this for pop-ups (CS:GO or opt-in for other games), I'll be pushing out an update shortly to ensure pop-ups can still run even if the plugin is configured to not use proxies for all pages (since the delayed load isn't necessary anymore) and edit this post. The new method will still use the proxy's popup functionality, but will avoid applying iframe / delayed load workarounds.
The current workarounds will remain available for backwards compatibility purposes, even though they're effectively obsolete.
Edit: 3.1.4 has been released, with the following changes:
- Popups will set the underlying panel's show value to false. This prevents the default panel from being displayed (mainly in non-CS:GO games, but should also prevent it if a CS:GO update enables the built-in MOTD panel again).
- New URL configuration option: proxy_popups. Only applies the proxy method to popups (implicitly enabled in CS:GO by default, otherwise must specify x-vgui-popup or use the appropriate include function); other pages will be passed through. This is intended as a popup-supported version of the none option, which will never do any processing.
Important note: There is a known issue with the Steam Client beta (with the new chat interface) where opening new popup windows does not work on any game. No known fix at the moment; you'll just have to sit tight until a workaround exists (which I would be happy to implement) or until Valve restores this functionality.