comctl32: initial theming tests

Roderick Colenbrander thunderbird2k at
Thu Sep 24 11:45:08 CDT 2009

> BTW. Do you plan to reregister all user32 classes on comctl32 load? How
> could this be done at user32 side - testing for something like
> IsThemeActive() while loading user32?

I have been toying with this a bit and trying to figure out how it
works. From MSDN info and info from a site which has good comctl32
info (
I have a basic idea on how it works.

According to MSDN the CreateWindow call performs some filtering and
depending on whether a manifest is around to override the windowclass
of lets say a Button, it creates a themed button. You might wonder
what it does about the window class registration. The Button class is
unregistered (I'll come to that a bit later) and I think that user32
then calls comctl32 its RegisterClassNameW function (this function is
not well documented but that page I mentioned, documents it well) to
re-register the Button class. I have no idea whether it is user32
which unregisters the Button class or whether RegisterClassNameW does

For sure we need tests for RegisterClassNameW IF we want to implement
our theming this way and I have a strong feeling that this is what
microsoft uses. If you search on google for RegisterClassNameW you
also notice within the first 10 results posts like
which makes me believe it really works this way.

I don't know user32/comctl32 that well but do you have suggestions for
tests? AJ suggested GetClassInfo tests (not sure what to look for) and
window class lookup order tests.


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