Создаём новый проект, У формы BorderStyle ставим bsNone.

И вот дальше исходник

unit Unit1;

interface

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

type
TForm1 = class(TForm)
procedure FormMouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
procedure FormMouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
private
{ Private declarations }
public
OldPoint : TPoint;
XResize : Boolean;
YResize : Boolean;
XYResize : Boolean;
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
OldPoint.X := X;
OldPoint.Y := Y;

If (OldPoint.X = Width - 1) And ((OldPoint.Y = Height - 1) or (OldPoint.Y = Height - 2) or (OldPoint.Y = Height - 3) or (OldPoint.Y = Height - 4) or (OldPoint.Y = Height - 5) or (OldPoint.Y = Height - 6) or (OldPoint.Y = Height - 7)) Then
XYResize := True;
If (OldPoint.X = Width - 2) And ((OldPoint.Y = Height - 1) or (OldPoint.Y = Height - 2) or (OldPoint.Y = Height - 3) or (OldPoint.Y = Height - 4) or (OldPoint.Y = Height - 5) or (OldPoint.Y = Height - 6) or (OldPoint.Y = Height - 7)) Then
XYResize := True;
If (OldPoint.X = Width - 3) And ((OldPoint.Y = Height - 1) or (OldPoint.Y = Height - 2) or (OldPoint.Y = Height - 3) or (OldPoint.Y = Height - 4) or (OldPoint.Y = Height - 5) or (OldPoint.Y = Height - 6) or (OldPoint.Y = Height - 7)) Then
XYResize := True;
If (OldPoint.X = Width - 4) And ((OldPoint.Y = Height - 1) or (OldPoint.Y = Height - 2) or (OldPoint.Y = Height - 3) or (OldPoint.Y = Height - 4) or (OldPoint.Y = Height - 5) or (OldPoint.Y = Height - 6) or (OldPoint.Y = Height - 7)) Then
XYResize := True;
If (OldPoint.X = Width - 5) And ((OldPoint.Y = Height - 1) or (OldPoint.Y = Height - 2) or (OldPoint.Y = Height - 3) or (OldPoint.Y = Height - 4) or (OldPoint.Y = Height - 5) or (OldPoint.Y = Height - 6) or (OldPoint.Y = Height - 7)) Then
XYResize := True;
If (OldPoint.X = Width - 6) And ((OldPoint.Y = Height - 1) or (OldPoint.Y = Height - 2) or (OldPoint.Y = Height - 3) or (OldPoint.Y = Height - 4) or (OldPoint.Y = Height - 5) or (OldPoint.Y = Height - 6) or (OldPoint.Y = Height - 7)) Then
XYResize := True;
If (OldPoint.X = Width - 7) And ((OldPoint.Y = Height - 1) or (OldPoint.Y = Height - 2) or (OldPoint.Y = Height - 3) or (OldPoint.Y = Height - 4) or (OldPoint.Y = Height - 5) or (OldPoint.Y = Height - 6) or (OldPoint.Y = Height - 7)) Then
XYResize := True;

If OldPoint.X = Width - 1 Then XResize := True;
If OldPoint.X = Width - 2 Then XResize := True;
If OldPoint.X = Width - 3 Then XResize := True;
If OldPoint.Y = Height - 1 Then YResize := True;
If OldPoint.Y = Height - 2 Then YResize := True;
If OldPoint.Y = Height - 3 Then YResize := True;
end;

procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
XResize := False;
YResize := False;
XYResize := False;
end;

procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
begin
If Not XYResize and not XResize and not YResize Then
Begin
cursor := crDefault;
If X = Width - 1 Then cursor := crSizeWE;
If X = Width - 2 Then cursor := crSizeWE;
If X = Width - 3 Then cursor := crSizeWE;
If Y = Height - 1 Then cursor := crSizeNS;
If Y = Height - 2 Then cursor := crSizeNS;
If Y = Height - 3 Then cursor := crSizeNS;

If (X = Width - 1) And ((Y = Height - 1) or (Y = Height - 2) or (Y = Height - 3) or (Y = Height - 4) or (Y = Height - 5) or (Y = Height - 6) or (Y = Height - 7)) Then
cursor := crSizeNWSE;
If (X = Width - 2) And ((Y = Height - 1) or (Y = Height - 2) or (Y = Height - 3) or (Y = Height - 4) or (Y = Height - 5) or (Y = Height - 6) or (Y = Height - 7)) Then
cursor := crSizeNWSE;
If (X = Width - 3) And ((Y = Height - 1) or (Y = Height - 2) or (Y = Height - 3) or (Y = Height - 4) or (Y = Height - 5) or (Y = Height - 6) or (Y = Height - 7)) Then
cursor := crSizeNWSE;
If (X = Width - 4) And ((Y = Height - 1) or (Y = Height - 2) or (Y = Height - 3) or (Y = Height - 4) or (Y = Height - 5) or (Y = Height - 6) or (Y = Height - 7)) Then
cursor := crSizeNWSE;
If (X = Width - 5) And ((Y = Height - 1) or (Y = Height - 2) or (Y = Height - 3) or (Y = Height - 4) or (Y = Height - 5) or (Y = Height - 6) or (Y = Height - 7)) Then
cursor := crSizeNWSE;
If (X = Width - 6) And ((Y = Height - 1) or (Y = Height - 2) or (Y = Height - 3) or (Y = Height - 4) or (Y = Height - 5) or (Y = Height - 6) or (Y = Height - 7)) Then
cursor := crSizeNWSE;
If (X = Width - 7) And ((Y = Height - 1) or (Y = Height - 2) or (Y = Height - 3) or (Y = Height - 4) or (Y = Height - 5) or (Y = Height - 6) or (Y = Height - 7)) Then
cursor := crSizeNWSE;
End;

If XYResize Then Begin
Width := X;
Height := Y; End Else Begin
If XResize Then
Width := X;
If YResize Then
Height := Y;
end;
end;

end.