Active Accessibility (COM) calls return differently depending if caller is a thread vs. a process. What?!

Question

I have code that uses Microsoft Active Accessbility to get information about the active window. Strangely, I can only enumerate all the controls in a window (in this case Internet Explorer) if I use a process. If I spawn a thread and call the EXACT same code, MSAA will return only a subset of controls. Usually just the menu bar and toolbars. The pane with the actual webpage does not get enumerated. Only information about the pane is returned and not its children. What could possibly cause this weird behavior?! Makes no sense.

Answer 1

The helper process will have its own UAC settings, while a spawned thread will use the UAC settings of the original process. IE7 and IE8 have special security measures that work in conjunction with UAC.