unit Unit1;interfaceusesWindows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,Dialogs, StdCtrls;typeTForm1 = class(TForm)Memo1: TMemo;procedure FormCreate(Sender: TObject);procedure FormMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);protected{这句的输入方法: Ctrl+空格; 输入 moused 确认; 然后执行 Shift+Ctrl+C}procedure MouseDown(Button: TMouseButton; Shift: TShiftState; X: Integer; Y: Integer); override;{这句的输入方法: Ctrl+空格; 输入 wmlbuttondo 确认; 然后执行 Shift+Ctrl+C}procedure WMLButtonDown(var Message: TWMLButtonDown); message WM_LBUTTONDOWN;end;varForm1: TForm1;implementation{$R *.dfm}procedure TForm1.FormCreate(Sender: TObject);
beginMemo1.Clear;
end;{响应 WM_LBUTTONDOWN 消息的方法 1: OnMouseDown 事件}
procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;Shift: TShiftState; X, Y: Integer);
beginMemo1.Lines.Add('OnMouseDown');
end;{响应 WM_LBUTTONDOWN 消息的方法 2: 覆盖父类的 MouseDown 方法}
procedure TForm1.MouseDown(Button: TMouseButton; Shift: TShiftState; X,Y: Integer);
begininherited; {可以去掉或下移这句再试}Memo1.Lines.Add('MouseDown');
end;{响应 WM_LBUTTONDOWN 消息的方法 3: 直接使用消息方法}
procedure TForm1.WMLButtonDown(var Message: TWMLButtonDown);
beginMemo1.Lines.Add('WM_LBUTTONDOWN');inherited; {可以去掉或上移这句再试}
end;end.

窗体文件:

object Form1: TForm1Left = 0Top = 0Caption = 'Form1'ClientHeight = 123ClientWidth = 233Color = clBtnFaceFont.Charset = DEFAULT_CHARSETFont.Color = clWindowTextFont.Height = -11Font.Name = 'Tahoma'Font.Style = []OldCreateOrder = FalseOnCreate = FormCreateOnMouseDown = FormMouseDownPixelsPerInch = 96TextHeight = 13object Memo1: TMemoLeft = 0Top = 0Width = 137Height = 123Align = alLeftLines.Strings = ('Memo1')ScrollBars = ssVerticalTabOrder = 0ExplicitHeight = 206end
end

后面还有更多响应消息的办法.