Commit 71d35d89 broke the way
WM_TAKE_FOCUS protocol is implemented: WM_MOUSEACTIVATE now replies
MA_NOACTIVATE by default when using HTCAPTION.

We use the WM_MOUSEACTIVATE -although Windows does not- regardless of
the way focus is changed to check whether a window wants focus, and
Windows sometimes changes focus regardless of the message reply.

Steam and the Wine system tray are affected for instance.
Signed-off-by: Rémi Bernon <rbernon@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>