Question:
How do I broadcast a message (such as WM_WININICHANGE)
to all top level Windows?
Answer:
The Windows API function SendMessage() takes a 4
parameters. The first is the window handle. To broadcast
to all top level Windows, use HWND_BROADCAST. The second
parameter is the message itself, and then the WParam and
the LParam parameters for the given message. For the
WM_WININICHANGE message, wParam should be zero, and LParam
should be either the address of a null terminated section
name that changed, or nil if you want each window to examine
all sections for the change. Passing a null value is not
recommended unless you have modified several sections due
to performance considerations.
Example:
var
s : array[0..64] of char;
begin
StrCopy(S, 'windows');
SendMessage(HWND_BROADCAST, WM_WININICHANGE, 0, LongInt(@S));
end;