Question

I tried to create button (child window) inside WM_NCCREATE message, and its position seemed to be created respected to screen coordinates, rather than client coordinates. At first, I thought WM_CREATE and WM_NCCREATE provide us the same handle to window, but this seem to be untrue. Therefore, can anyone explain me the differences between WM_CREATE and WM_NCCREATE messages? Also what are the differences between handle to window in WM_CREATE and in WM_NCCREATE?

Answer 1

Per MSDN:

WM_NCCREATE:

Sent prior to the WM_CREATE message
when a window is first created.

Return Value:

If an application processes this
message, it should return TRUE to
continue creation of the window. If
the application returns FALSE, the
CreateWindow or CreateWindowEx
function will return a NULL handle.

WM_CREATE:

Sent when an application requests that
a window be created by calling the
CreateWindowEx or CreateWindow
function. (The message is sent before
the function returns.) The window
procedure of the new window receives
this message after the window is
created, but before the window becomes
visible.

Return Value:

If an application processes this
message, it should return zero to
continue creation of the window. If
the application returns –1, the window
is destroyed and the CreateWindowEx or
CreateWindow function returns a NULL
handle.