您好,

這問題蠻有趣的, 記得好像有元件可以做到, 但可能要再花時間 google 一下.
剛剛用自己的想法測了一下 tedit, 雖然不是拖动边框, 而是按住元件內任何一點,
來托拉增減元件寛度.
我知道這絶對不是您要的解答, 但頗好玩的
參考一下

var
ox, ii : integer;

procedure TForm1.Edit1MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
if ox=0 then begin
ox := x;
ii := 1;
end;
end;

procedure TForm1.Edit1MouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
ox :=0;
ii :=0;
end;

procedure TForm1.Edit1MouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
begin
if ii=1 then begin
if ox =0 then
ox :=x
else begin
edit1.Width := edit1.Width x-ox;
ox := 0;
end;
end;
end;

===================引 用 wq236589 文 章===================

您好,

果然就有大大提供現成的元件. 謝謝啦.

雖然我的工作中好像用不這這個功能, 為了好玩,
剛剛再改了一下我的測試, 可行耶, 也請參考一下這個 diy 版本.

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;

type
TForm1 = class(TForm)
Edit1: TEdit;
procedure Edit1StartDrag(Sender: TObject; var DragObject: TDragObject);
procedure Edit1MouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
procedure Edit1StartDock(Sender: TObject; var DragObject: TDragDockObject);
procedure Edit1MouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
procedure Edit1MouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;
ox, oy : integer;
in_drag, in_drag_x, in_move, in_drag_y : boolean;

implementation

{$R *.dfm}

procedure TForm1.Edit1StartDrag(Sender: TObject;
var DragObject: TDragObject);
begin
ox := 0;
oy := 0;

end;

procedure TForm1.Edit1MouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
begin
if (edit1.Width-x<10) and (edit1.Height-y<10) then edit1.cursor := crsizenwse
else if edit1.Width-x<10 then edit1.cursor := crsizewe
else if edit1.Height-y<10 then edit1.cursor := crsizens
else edit1.Cursor := crdefault;
if in_drag_x then begin
if ox =0 then
ox := x
else begin
edit1.Width := edit1.Width x-ox;
ox := 0;
end;
end;
if in_drag_y then begin
if oy =0 then
oy := y
else begin
edit1.height := edit1.Height y-oy;
oy :=0;
end;
end;
if in_move then begin
if ox =0 then begin
ox := x;
oy := y;
end
else begin
edit1.left := edit1.left x-ox;
edit1.top := edit1.top y-oy;
ox := 0;
oy :=0;
end;
end;
end;

procedure TForm1.Edit1StartDock(Sender: TObject; var DragObject: TDragDockObject);
begin
ox := 0;
oy := 0;
end;

procedure TForm1.Edit1MouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
begin
if not in_drag then begin
if edit1.Width-x<10 then begin
in_drag_x := true;
edit1.cursor := crsizewe;
end;
if edit1.Height-y<10 then begin
in_drag_y := true;
edit1.cursor := crsizens;
end;
if in_drag_x and in_drag_y then edit1.cursor := crsizenwse;
if in_drag_x or in_drag_y then
in_move := false
else begin
in_move := true;
edit1.Cursor := crsizeall;
end;
end;
ox := x;
oy := y;
end;

procedure TForm1.Edit1MouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
begin
in_drag := false;
in_drag_x := false;
in_drag_y := false;
in_move := false;
edit1.cursor := crdefault;
end;

end.