C# Windows Forms: How to filter WM_ACTIVATE and WM_NCACTIVATE messages?

[C# Programming]

Hey all,

I want to intercept windows message that is sent to my program when form is deactivated (or activated, no matter). I can intercept mouse clicks etc. using regular message filter, but I can't intercept WM_NCACTIVATE or WM_ACTIVATE messages, why is that?

I'm trying something like that:


[SecurityPermission(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)]
public class MessageFilter : IMessageFilter
{
private const int WM_ACTIVATE = 0x006;
private const int WM_NCACTIVATE = 0x086;

public bool PreFilterMessage(ref Message m)
{
if(m.Msg == WM_NCACTIVATE)
return true;
return false;
}
}

and then in Main:

MessageFilter mf = new MessageFilter();
Application.AddMessageFilter(mf);


I can see using debugger that it doesn't react on activation and deactivation of my form. How to do it correclty?