I know that CreateWindow and CreateWindowEx sends a WM_CREATE message. Is WM_CREATE always the first message that arrives to the message handling callback function?

From running the code a few times, i determined that the first number that uiMsg gets is 36 (the first message that gets sent to the callback function). In hex, this represents 0x0024, and looking in winuser.h (where the WM_ are defined) it appears that the first message that gets sent is WM_GETMINMAXINFO (which makes since, because it needs the window''s dimensions before creating the window). so all in all, here is what gets called (in order):

uiMsg call name hex equivalent
36 : WM_GETMINMAXINFO 0x0024
129 : WM_NCCREATE 0x0081
131 : WM_NCCALCSIZE 0x0083
1 : WM_CREATE 0x0001

so there ya have it :-D
realize of course that it really isn''t necessary to put WM_GETMINMAXINFO or WM_NCCCREATE or any of those in your winproc, i don''t think they are really necessary info