Otherwise we would leak a reference for both of these if the ifstub was already created.
Fix the FIXME in the code by releasing the stub manager if necessary.

and fixup the places that depended on the old behaviour.

to fixup the IID used to connect to the server and fix somewhat common
"err:rpc:RPCRT4_OpenBinding" messages.

This makes sure the property is set to the right value even when order in listbox is changed.

Remove struct msi_listbox_item as it only contains 1 element now.

Additional tests indicate that native doesn't touch previously set
properties.

keyboard shortcuts work correctly and so that tabbing through the
controls behaves as the user expects.

For builtin dlls prepend the system directory.