Question

I was reading some tutorials and I met the following structure:

protected override void WndProc( ref Message m )
{
    ...

    base.WndProc( ref m );
}

and for example:

private const int WM_DWMCOMPOSITIONCHANGED = 0x31e;

what s the meaning of 0x31e. some documentation for it?

Answer 1

It’s the value of the constant you highlighted.

http://msdn.microsoft.com/en-us/library/windows/desktop/dd388199%28v=vs.85%29.aspx

The actual hexadecimal value has no special meaning other than that it identifies the WM_DWMCOMPOSITIONCHANGED message.

There are many other window messages in the Windows API – all messages that start with WM_ and then some more. You can open winuser.h and look for them but you’ll have to read the individual message documentations to learn what they do. winuser.h only contains the declarations of the constants.