[win32] - about message loop

Question

i'm confused with message loop :(
see these function:
//Message Loop
WPARAM MessageLoop()
MSG msgEvents;
while(GetMessage(&msgEvents, NULL, 0, 0) > 0)
if(IsChild(GetForegroundWindow(),msgEvents.hwnd)==TRUE || GetForegroundWindow()==msgEvents.hwnd)
if(IsDialogMessage(GetForegroundWindow(), &msgEvents) == TRUE)
TranslateMessage(&msgEvents);
DispatchMessage(&msgEvents);
return msgEvents.wParam;
i did several tests and seems:
1 - if i press Alt key, the underline(on menu bar) is showed. if i unpress it, the underline isn't showed.
2 - when i do Alt + H(i have on test) the message is called twice.
what i miss with message loop?
(if i take off that 2 if's, the problem of the alt key goes away)
is possible the Alt key, with that message loop, been called twices?

Answer 1

I think your logic is wrong for IsDialogMessage.  I say this based on these two things from the
IsDialogMessage documentation.
Because the IsDialogMessage function performs all necessary translating and dispatching of messages, a message processed by IsDialogMessage
must not be passed to the TranslateMessage or DispatchMessage function.
If the message has been processed, the return value is nonzero.
Based on that, I think your logic should be:
if (!IsDialogMessage(GetForegroundWindow(), &msgEvents))
TranslateMessage(&msgEvents);
DispatchMessage(&msgEvents);
IsDialogMessage may handle the message, and when that has happens, you must not process the message.  Otherwise you risk processing the message twice.
And in the reverse case, you are getting messages and not dispatching them -- essentially dropping them on the floor.  This also seems very wrong.
Extra:  It also seems wrong to return a field of an uninitialized msgEvents structure when GetMessage returns 0.