IE 7 and later versions always use a tab to show the web site. So even if you think you are not opening any tab, you have at least one tab open. This happens even if you disable tab browsing. This is by design in IE 7 and later versions.
1st iexplore.exe = main frame window
2nd iexplore.exe = 1st tab inside the main frame
3rd iexplore.exe = 2nd tab.... and so on.
The iexplore.exe instance for main frame window has no SCODEF parameter.
The iexplore.exe instance for tabs has SCODEF value indicating which main frame window it belongs to. (In case two or more mainframe IE windows are open).
Have a nice day
Edited by Romeo29, 17 October 2010 - 10:58 PM.