c# - WinForms child form to another process

Question

I'm trying to create child form on other process form without activation, everything is ok except that my form appearing in front of screen when showing - after f.Visible=true - but i need to keep both of them somewhere behind.

Here's code:

public class OSD {
    public class OSD_form:Form {
        protected override bool ShowWithoutActivation {
            get { return true; }
        }
        protected override CreateParams CreateParams {
            get {
                CreateParams p=base.CreateParams;

                //p.Style |= 0x40000000; // WS_CHILD
                p.ExStyle|=0x8000000; // WS_EX_NOACTIVATE
                p.ExStyle|=0x00080000; // WS_EX_LAYERED
                p.ExStyle|=0x0020; // WS_EX_TRANSPARENT

                return p;
            }
        }
    }
    private OSD_form f=null;
    public IntPtr AttachedTo=IntPtr.Zero;

    public OSD() {
        f=new OSD_form();

        f.FormBorderStyle=FormBorderStyle.None;
        f.ShowInTaskbar=false;
    }

    public void Show() {
        long l2=winapi.GetWindowLong(f.Handle,winapi.GWL_EXSTYLE);
        l2|=winapi.WS_EX_LAYERED;
        l2|=winapi.WS_EX_TRANSPARENT;
        winapi.SetWindowLong(f.Handle,winapi.GWL_EXSTYLE,new IntPtr(l2));
        winapi.SetLayeredWindowAttributes(f.Handle,0,(255*90)/100,winapi.LWA_ALPHA);

        window w=new window(AttachedTo);
        f.Width=160;
        f.Height=60;
        f.Left=w.Client.Left+4;
        f.Top=w.Client.Top+4;

        f.Show(new WindowWrapper(AttachedTo));

        f.Visible=true;

    }
}