0x0118消息就是WM_SYSTIMER

http://social.msdn.microsoft.com/Forums/vstudio/en-US/c0f9bac9-d211-4b8b-ba99-f5a0ed0d2e0a/what-is-wm-id-code-0x0118?forum=vclanguage

编辑框出现输入光标时,产生的消息.

0x0118 would be the undocumented WM_SYSTIMER, which appears to be used for caret blinks.

0x0118是一个undocument 消息， 微软没有记录。
但在一些库的源码中可以看到，比如ATL的库文件atlapp.h中，如此写到：
static BOOL IsIdleMessage(MSG* pMsg)
{
// These messages should NOT cause idle processing
switch(pMsg->message)
{
case WM_MOUSEMOVE:
#ifndef _WIN32_WCE
case WM_NCMOUSEMOVE:
#endif //!_WIN32_WCE
case WM_PAINT:
case 0x0118: // WM_SYSTIMER (caret blink)
return FALSE;
}

return TRUE;
}
由此可知0x0118是WM_SYSTIMER 消息

INFO: Windows WM_SYSTIMER Message Is an Undocumented Message
Q108938
The information in this article applies to:
Microsoft Win32 Software Development Kit (SDK)
Microsoft Windows Software Development Kit (SDK) 3.1

SUMMARY
The WM_SYSTIMER message in Windows is an undocumented system message; it should not be trapped or relied on by an application. This message can occasionally be viewed in Spy or in CodeView while debugging. Windows uses the WM_SYSTIMER message internally to control the scroll rate of highlighted text (text selected by the user) in edit controls, or highlighted items in list boxes.
NOTE: The WM_SYSTIMER message is for Windows's internal use only and can be changed without prior notice.