IECUSTOMIZER
Here's the test plan to show how the Google toolbar hijacks the Toolbar layout in IE7 (untested in 6)
Start IE7 and unload the Google toolbar (if loaded) and just to be safe, any other third-party toolbars that you have installed. Arrange your remaining IE7 toolbars to your pleasure. I have the Menus and Links toolbars on the top line. Close IE7 to save your toolbar layout.
Open IE7 and it should show the last retained toolbar layout.... as expected.
Load the Google toolbar. Place it on a line of its own. Close IE to save the Toolbar layout..
Open IE7 and you will see that the toolbar layout has changed... All toolbars are displayed on their own lines...
Select the Tools>Manage Addons menu and find and disable the 'Google Toolbar Browser Helper' (the BHO part). Re-arrange the toolbars to your pleaseure.... note that the Google toolbar is still visible even though the BHO component has been disabled. (acutually it is still in memory, but it won't be loaded the next time the browser is started).
Close IE7 to save your toolbar layout.
Open IE7 and this time it should have retained your saved toolbar layout.
Conclusion - The Google toolbar hijacks ITBarLayout from within its satelite BHO. Disabling the satelite BHO of the Google toolbar returns toolbar layout behavior.
Other known hijackers - Del.icio.us toolbar
Seems to be a misunderstanding by toolbar developers to use a satelite BHO to write to ITBarLayout to force their toolbars to be displayed in the toolbar, dispite the users preferences.
For those of you with RegMon.exe - Place a hook on the satelite bho to track the registry writes to ITBarLayout.
Regards.