What's in a Pop-Up?

Last week, I posted about how some of our strict group policy settings on our Terminal Services RemoteApp deployment were causing some difficulty using some web-based applications, like our time card application. As I continued to use the application through RemoteApp, I found another hiccup in the GPO settings - the lack of the application to be able to pop up additional windows for some special tasks.

I started with looking at all the GPO settings related to the Pop-up Blocker. There are several - Pop-up allow list, Turn off Managing Pop-up Allow list, Turn off pop-up management. After tweaking and disabling those, I still couldn't get the new task window to appear.

In order to leave no stone unturned, I proceeded to look closely at every IE setting that was configured and came across "Disable Open in New Window menu option", under User Config - Policies - Admin Templates - Windows Components - Internet Explorer - Browser Menus. The provided explanation leads one to believe that it only hides the option from the shortcut menu to prevent users from manually launching a new window from that browser session. However, it also prevents an application from launching the window as well.

Since the Pop-Up Blocker itself wasn't the problem, I was curious about what the Pop-up Blocker actually blocks. MSDN has some in-depth explanations about how the Pop-up Blocker works, but it comes down to this: Pop-up blocking prevents new browser windows being opened automatically using a script. Pop-up Blocker doesn't affect browser activities when they are initiated by a user action (such as clicking a button or hyperlink), when opened in the Trusted sites and Local intranet zones, or when opened by other applications running on the local computer.

It does block script methods that call the following:

• window.open
• window.showHelp
• window.showModalDialog
• window.showModelessDialog
• window.external
• window.NavigateAndFind

An interesting note was that pop-ups created with "window.createPopup" are unaffected by the Pop-up Blocker. That doesn't make sense to me, but I'm not a developer and I'm sure there is something I'm missing.

In my case, changing the Pop-up settings were moot, because the specific policy blocking the "window.open" command trumped any attempt to open a new windows, specifically those initiated by users.