[0000 0000 ~ 0000 03ff] WM_NULL, WM_CREATE, ... : Messages reserved for use by the system.
[0000 0400 ~ 0000 07ff] WM_USER ~ WM_USER+0x03ff : Integer messages for use by private window classes.
[0000 0800 ~ 0000 bfff] WM_APP ~ WM_APP +0x03ff : Messages available for use by applications
[0000 c000 ~ 0000 ffff] RegisterWindowMessage() : String messages for use by applications.
[0001 0000 ~ ffff ffff] Reserved by the system.
[0000 0400 ~ 0000 07ff] WM_USER ~ WM_USER+0x03ff : Integer messages for use by private window classes.
[0000 0800 ~ 0000 bfff] WM_APP ~ WM_APP +0x03ff : Messages available for use by applications
[0000 c000 ~ 0000 ffff] RegisterWindowMessage() : String messages for use by applications.
[0001 0000 ~ ffff ffff] Reserved by the system.
WM_USER
WM_APP
WM_reg
WM_sys