控件开发：关于组合控件的mousedown。 (100分)

我需要开发一个具有阴影的一个按钮控件，我用了两个panel 重叠，就象ghost6。0中
的那种按钮，外面一个用亮色，里面一个用暗色（表示阴影），当我在外面panel按下mouse时时，
我将两个控件重合，当松开mouse时，恢复原状。
请教各位及格问题：
1.我是继承自tpanel，进行开发，还是twincontrol开发。
2.我如何写mousedown事件，现在是这样的情况：
我写出来的那个onmousedown事件，然后我用一个程序来测试该组件，我发现我如果
不在测试程序中该按钮的mousedown写一句语句（随便什么语句，比如showmessage(''aa)之类的）
这个组件的setOnMousedown过程不执行，如果写一条语句，那么你还没点击该按钮时，这个过程就
执行了，这是怎么会事，我把程序代码贴出来，大家帮帮忙。谢谢了！！！
unit ShadowButton;

interface

uses
Windows, Messages, SysUtils,StdCtrls, Classes, Controls, ExtCtrls,Graphics;

type
TShadowButton = class(twincontrol)

private
FPanelOutside:tpanel;
FpanelInside:tpanel;
{ Private declarations }
protected
procedure wmsize(var message:twmsize);message wm_size;
function GetOnMousedown:tmouseevent;
procedure SetOnMousedown(value :tmouseevent);
{ Protected declarations }
public
constructor create(Aowner:tcomponent);override;
destructor destroy;override;
{ Public declarations }
published
property Onmousedown:tmouseevent read getonmousedown write setonmousedown;
{ Published declarations }
end;

procedure Register;

implementation

procedure Register;
begin
RegisterComponents('Standard', [TShadowButton]);
end;

constructor Tshadowbutton.create(Aowner:tcomponent);
begin
inherited create(aowner);
bevelouter:=bvnone;

fpaneloutside:=tpanel.Create(self);
fpanelinside:=tpanel.Create(self);

with fpanelinside do
begin
Parent:=self;
Color :=clblack;
bevelouter:=bvNone;
Left :=fpaneloutside.Left +8;
top:=fpaneloutside.Top +8;
width:=fpaneloutside.Width;
height:=fpanelinside.Height ;
end;

fpaneloutside.Parent:=self;
fpaneloutside.Color :=clblue;
fpaneloutside.bevelouter:=bvNone;
width:=fpaneloutside.Width;
height:=fpanelinside.Height ;
end;

procedure tshadowbutton.wmsize(var message:twmsize);
begin
inherited;
fpaneloutside.Width :=message.Width-15;
fpaneloutside.Height :=message.Height-15;
fpanelinside.Width :=message.Width-15;
fpanelinside.Height :=message.Height-15;
end;

destructor tshadowbutton.destroy;
begin
fpanelinside.Free;
fpaneloutside.Free;
inherited destroy;
end;

function tshadowbutton.GetOnMousedown:tmouseevent;
begin
result :=fpaneloutside.OnMouseDown;
end;
//就在这个过程里面里出问题。
procedure tshadowbutton.setOnMousedown(value:tmouseevent);
begin
fpaneloutside.OnMouseDown :=value;
fpaneloutside.Left :=fpanelinside.Left;
fpaneloutside.top :=fpanelinside.top;
end;

你可以重载MouseDown函数来处理，
没必要搞的这么复杂。
interface
procedure tshadowbutton.MouseDown(Button: TMouseButton;
Shift: TShiftState; X, Y: Integer); override;

implementation
procedure tshadowbutton.MouseDown(Button: TMouseButton;
Shift: TShiftState; X, Y: Integer;
begin
fpaneloutside.Left :=fpanelinside.Left;
fpaneloutside.top :=fpanelinside.top;
end;

to 鲁小班 ，我第一次就是使用的你这种方法，但是问题就是当我点击在fpaneloutside上
不触发这个mousedown事件，只有点击在除了fpaneloutside，和fpanelinside时，才触发
mousedown事件。
恳请大家帮忙。

建议你从TCustomPanel继承下来，而且只需要一个Panel类成员，这个成员是前景，
而控件本身是背景，另外你也不要重载MouseDown方法而是直接重载WM_LButtonDown消息。

现在可以了，不过有点复杂，不知道有什么更简单的办法.

unit ShadowButton;

interface

uses
Windows, Messages, SysUtils,StdCtrls, Classes, Controls, ExtCtrls,Graphics;

type
TShadowButton = class(twincontrol)

private
FPanelOutside:tpanel;
FpanelInside:tpanel;
{ Private declarations }
protected
procedure wmsize(var message:twmsize);message wm_size;[red]
procedure wmlbuttondown( var message:TWMLButtonDown);message wm_lbuttondown;
procedure wmlbuttonup( var message:TWMLButtonup);message wm_lbuttonup;
procedure mousedown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
procedure mouseup(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);[/red]

// function GetOnMousedown:tmouseevent;
// procedure SetOnMousedown(value :tmouseevent);
{ Protected declarations }
public
constructor create(Aowner:tcomponent);override;
destructor destroy;override;
{ Public declarations }
published
// property Onmousedown:tmouseevent read getonmousedown write setonmousedown;
{ Published declarations }
end;

procedure Register;

implementation

procedure Register;
begin
RegisterComponents('Standard', [TShadowButton]);
end;

constructor Tshadowbutton.create(Aowner:tcomponent);
begin
inherited create(aowner);
bevelouter:=bvnone;

fpaneloutside:=tpanel.Create(self);
fpanelinside:=tpanel.Create(self);
fpaneloutside.OnMouseDown := mousedown;
fpanelinside.OnMouseDown := mousedown;
fpaneloutside.OnMouseUp := mouseup;
fpaneloutside.OnMouseUp := mouseup;
with fpanelinside do
begin
Parent:=self;
Color :=clblack;
bevelouter:=bvNone;
Left :=fpaneloutside.Left +8;
top:=fpaneloutside.Top +8;
width:=fpaneloutside.Width;
height:=fpanelinside.Height ;
end;

fpaneloutside.Parent:=self;
fpaneloutside.Color :=clblue;
fpaneloutside.bevelouter:=bvNone;
width:=fpaneloutside.Width;
height:=fpanelinside.Height ;
end;

procedure tshadowbutton.wmsize(var message:twmsize);
begin
inherited;
fpaneloutside.Width :=message.Width-15;
fpaneloutside.Height :=message.Height-15;
fpanelinside.Width :=message.Width-15;
fpanelinside.Height :=message.Height-15;
end;

destructor tshadowbutton.destroy;
begin
fpanelinside.Free;
fpaneloutside.Free;
inherited destroy;
end;
{
function tshadowbutton.GetOnMousedown:tmouseevent;
begin
result :=fpaneloutside.OnMouseDown;
end;
//¾ÍÔÚÕâ¸ö¹ý³ÌÀïÃæÀï³öÎÊÌâ¡£
procedure tshadowbutton.setOnMousedown(value:tmouseevent);
begin
fpaneloutside.OnMouseDown :=value;
fpaneloutside.Left :=fpanelinside.Left;
fpaneloutside.top :=fpanelinside.top;
end;
}
[red]procedure tshadowbutton.wmlbuttondown(var message:TWMLButtonDown);
begin
inherited;
fpaneloutside.Left :=fpanelinside.Left;
fpaneloutside.top :=fpanelinside.top;

end;
procedure tshadowbutton.wmlbuttonup(var message:tWmlbuttonup);
begin
inherited;
fpaneloutside.Left :=fpanelinside.Left-8;
fpaneloutside.top :=fpanelinside.top-8;

end;
procedure tshadowbutton. mousedown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
if button = mbLeft then
begin
sendmessage(self.Handle,wm_lbuttondown,0,0);
end;
end;
procedure tshadowbutton. mouseup(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
if button = mbLeft then
begin
sendmessage(self.Handle,wm_lbuttonup,0,0);
end;
end;[/red]
end.

谢谢各位：to aizb，一开始，我也和你一样想，但是如果只中一个panel，然后控件本身
那个panel做阴影，因为两个panel的left一样，所以效果为里面一个框，外面一个框，没有立体感觉
，但是你提的第二点我觉得应该有用，我试一下，谢谢先。
to xeen, 非常感谢你，辛苦你了，也很感谢大富翁，你的代码我马上试一下。

接受答案了.