Hi all,
I need to intercept WM_WINDOWPOSCHANGING and modify one of its parameters,
specifically I have (depending on a flag set somewhere in my program) to
allow or disallow the change in Z order of any window.
Please note that there's no other way for me, if I just needed one window
to remain on top, it would be easy.. but I instead need that if the user
clicks on a window, this gets the keyboard focus but does not change the
Z orders at all (of course I need to provide this "feature" only in certain
situations, depending on the forementioned flag set by my application).
The most natural way would be to use a system-wide WH_CALLWNDPROC hook,
intercept WM_WINDOWPOSCHANGING, and "or" lParam->flags with SWP_NOZORDER.
Very frustratingly, there's the usual exception to the rule that makes
my life as Win32 programmer always much more complicated than it should
be. Namely, the MSDN docs say:
"The hook procedure can examine the message; it cannot modify it".
This is a specific limitation placed by Microsoft on WH_CALLWNDPROC.
So a WH_CALLWNDPROC hook is totally useless for me. :/
I could use a WH_GETMESSAGE hook instead .. but some messages, namely
the one that I need to intercept/modify, do not pass through GetMessage,
but is sent directly to the target window proc. 
Would a WH_CBT hook solve my problem? I don't think so, since I could
not see anything Z order related in the list of HCBT_* we can specify,
but I sure hope to be wrong!
So, what are my last options?
# find/intercept all WndProc procedures in the system, and hook them
with my code? [looks overkill]
# place a global/kernel API hook at SendMessageA and SendMessageW?
but both would work only if the user has administrator privileges,
right? ( I want 9x/and NT/2000/XP compatibility. I could give up
95 and NT.. but not 98,ME,2000 and XP.
Please help.. I need some clever hints.
Greets,
John
