Delphi uses custom handle to process messages

Unit ucallhwnd;interfaceuses  Classes, Messages, windows;const  wm_user_msg = wm_user + 1;type  Tcallhwnd = Class (TObject)  private    fhwnd:thandle;  Protected    Procedure Dousermessage (var amsg:tmessage);  Public    constructor Create;    destructor Destroy; Override;    Call test    function Callhwndtest:boolean;  end;implementation{tcallhwnd}function tcallhwnd.callhwndtest:boolean;begin  Result: = PostMessage (Fhwnd, WM_ User_msg, 1, 2) end;constructor tcallhwnd.create;begin  Fhwnd: = Allocatehwnd (dousermessage); end;destructor Tcallhwnd.destroy;begin  Deallocatehwnd (fhwnd);  Inherited;end;procedure Tcallhwnd.dousermessage (var amsg:tmessage); begin  If amsg.msg = wm_user_msg  Then Begin    //amsg.lparam 2    //amsg.wparam 1    //do something  end  else    amsg.result: = DefWindowProc (Fhwnd, Amsg.msg, Amsg.wparam, Amsg.lparam); End;end.

　　

Delphi uses custom handle to process messages