这里有个控件的源代码，非常好用，可惜焦点在这个控件上时不透明，你可以试着改一下。
unit RbsWiredEdit;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls;
const
TWM_RbsInvalidate=WM_USER+1;
type
TRbsWiredEdit = class(TEdit)
private
{ Private declarations }
procedure RbsInvalidate(var Message:TMessage); message
TWM_RbsInvalidate;
procedure CNCTLCOLOREDIT(var Message:TWMCTLCOLOREDIT); message
CN_CTLCOLOREDIT;
procedure WMEraseBkgnd(var Message: TWMEraseBkgnd); message WM_ERASEBKGND;
procedure WMMove(var Message: TMessage); message WM_MOVE;
protected
{ Protected declarations }
FTransparent: boolean;
procedure CreateWnd; override;
procedure CreateParams(var Params: TCreateParams); override;
procedure DoExit; override;
procedure DoEnter; override;
public
{ Public declarations }
constructor Create(AOwner: TComponent); override;
procedure Invalidate; override;
published
{ Published declarations }
end;
procedure Register;
implementation
constructor TRbsWiredEdit.Create(AOwner:TComponent);
begin
inherited create(AOwner);
ftransparent:=true;
end;
procedure TRbsWiredEdit.CreateWnd;
begin
inherited CreateWnd;
if fTransparent then
begin
SetWindowLong(Parent.Handle, GWL_STYLE,
GetWindowLong(Parent.Handle, GWL_STYLE) and not WS_CLIPCHILDREN);
end;
end;
procedure TRbsWiredEdit.RbsInvalidate(var Message:TMessage);
var r:TRect;
begin
if (Parent<>nil) and FTransparent then
begin
r:=ClientRect;
r.TopLeft:=Parent.ScreenToClient(ClientToScreen(r.TopLeft));
r.BottomRight:=Parent.ScreenToClient(ClientToScreen(r.BottomRight));
RedrawWindow(Handle,nil,0,RDW_FRAME+RDW_INVALIDATE);
end;
end;
procedure TRbsWiredEdit.CNCTLCOLOREDIT(var Message:TWMCTLCOLOREDIT);
begin
if FTransparent then
with Message do
begin
SetBkMode(ChildDC,Windows.TRANSPARENT);
Result:=GetStockObject(HOLLOW_BRUSH)
end
else inherited;
end;
procedure TRbsWiredEdit.WMEraseBkgnd(var Message:TWMERASEBKGND);
begin
if FTransparent and not (csDesigning in ComponentState) then
PostMessage(Handle,TWM_RbsInvalidate,0,0)
else inherited;
end;
procedure TRbsWiredEdit.WMMove(var message:TMessage);
begin
inherited;
if FTransparent then SendMessage(Handle,TWM_RbsInvalidate,0,0)
else Invalidate;
end;
procedure TRbsWiredEdit.CreateParams(var Params:TCreateParams);
begin
inherited CreateParams(Params);
if (CsDesigning in ComponentState) then exit;
with Params do
begin
ExStyle:=ExStyle or WS_EX_TRANSPARENT;
end;
end;
procedure TRbsWiredEdit.DoExit;
begin
inherited;
FTransparent:=true;
SetCursor(0);
RecreateWnd;
end;
procedure TRbsWiredEdit.DoEnter;
var exstyle,stdstyle:longint;
begin
inherited;
Ftransparent:=false;
StdStyle:= Windows.GetWindowLong(handle, GWL_EXSTYLE);
exStyle:= StdStyle and not WS_EX_TRANSPARENT;
Windows.SetWindowLong(handle, GWL_EXSTYLE, exStyle);
invalidate;
end;
procedure TRbsWiredEdit.Invalidate;
begin
if FTransparent then SendMessage(Handle,TWM_RbsInvalidate,0,0)
else inherited;
end;
procedure Register;
begin
RegisterComponents('Rombest', [TRbsWiredEdit]);
end;
end.