Merge branch 'mdi_horizontal_scrolling' into develop

5 files changed, 690 insertions, 526 deletions

diff --git a/prototypes/mdi/fpg_mdi.pas b/prototypes/mdi/fpg_mdi.pas
index ac127a33..88bb4d33 100644
--- a/prototypes/mdi/fpg_mdi.pas
+++ b/prototypes/mdi/fpg_mdi.pas
@@ -9,357 +9,398 @@ uses
   fpg_button;
 
 type
-	// forward declarations
-	TfpgMDIChildForm = class;
-
-
-	TfpgMDIWorkArea = class(TfpgWidget)
-	private
-		FHorBar: TfpgScrollbar;
-		FVerBar: TfpgScrollbar;
-		FList: TList;
-		FActiveWindow: TfpgMDIChildForm;
-		procedure InternalMsgFreeMe(var msg: TfpgMessageRec); message FPGM_FREEME;
-		procedure SetActiveWindow(AValue: TfpgMDIChildForm);
-		function GetChildWindowCount: integer;
-	protected
-		procedure HandlePaint; override;
-		procedure PositionScrollBars;
-	public
-		constructor Create(AOwner: TComponent); override;
-		destructor Destroy; override;
-		function AddWindow(AWindowClass: TfpgFrameClass): TfpgFrame;
-		property ActiveWindow: TfpgMDIChildForm read FActiveWindow write SetActiveWindow;
-		property ChildWindowCount: integer read GetChildWindowCount;
-	end;
-
-
-	TfpgMDIChildForm = class(TfpgWidget)
-	private
-		{@VFD_HEAD_BEGIN: MDIChildForm}
-		Panel1: TfpgPanel;
-		bevLeft: TfpgBevel;
-		Bevel2: TfpgBevel;
-		bevBottom: TfpgBevel;
-		Bevel4: TfpgBevel;
-		bevRight: TfpgBevel;
-		Button1: TfpgButton;
-		Button2: TfpgButton;
-		Button3: TfpgButton;
-		Button4: TfpgButton;
-		bvlClientArea: TfpgBevel;
-		{@VFD_HEAD_END: MDIChildForm}
-		FMDIWorkArea: TfpgMDIWorkArea;
-		FWindowTitle: TfpgString;
-		FIsMouseDown: boolean;
-		FLastPos: TPoint;
-		FActive: boolean;
-		procedure SetWindowTitle(AValue: TfpgString);
-		procedure TitleMouseMove(Sender: TObject; AShift: TShiftState; const AMousePos: TPoint);
-		procedure TitleMouseUp(Sender: TObject; AButton: TMouseButton; AShift: TShiftState; const AMousePos: TPoint);
-		procedure TitleMouseDown(Sender: TObject; AButton: TMouseButton; AShift: TShiftState; const AMousePos: TPoint);
-		procedure TitleMouseExit(Sender: TObject);
-		procedure CloseMDIWindowClicked(Sender: TObject);
-		procedure SetActive(AValue: boolean);
-	protected
-		property Active: boolean read FActive write SetActive;
-	public
-		constructor Create(AOwner: TfpgMDIWorkArea); reintroduce;
-		property WindowTitle: TfpgString read FWindowTitle write SetWindowTitle;
-		procedure SetClientFrame(AFrame: TfpgFrame);
-		procedure UpdateWindowTitle;
-		procedure Close;
-	end;
+
+  TfpgMDIChildMoveEvent = procedure(Sender: TObject; const rec: TfpgMoveEventRec) of object;
+
+  // forward declarations
+  TfpgMDIChildForm = class;
+
+
+  TfpgMDIWorkArea = class(TfpgWidget)
+  private
+    FHorBar: TfpgScrollbar;
+    FVerBar: TfpgScrollbar;
+    FList: TList;
+    FActiveWindow: TfpgMDIChildForm;
+    FScrollingHorizonal: Boolean;
+    FLastHorizonalPos: integer;
+    procedure InternalMsgFreeMe(var msg: TfpgMessageRec); message FPGM_FREEME;
+    procedure SetActiveWindow(AValue: TfpgMDIChildForm);
+    function GetChildWindowCount: integer;
+    procedure MDIChildMoved(Sender: TObject; const rec: TfpgMoveEventRec);
+    function CalcVirtualWidth: integer;
+    procedure HorizontalScrollBarScrolled(Sender: TObject; position: integer);
+  protected
+    procedure HandlePaint; override;
+    procedure HandleResize(AWidth, AHeight: TfpgCoord); override;
+    procedure PositionScrollBars;
+  public
+    constructor Create(AOwner: TComponent); override;
+    destructor Destroy; override;
+    function AddWindow(AWindowClass: TfpgFrameClass): TfpgFrame;
+    procedure CascadeWindows;
+    property ActiveWindow: TfpgMDIChildForm read FActiveWindow write SetActiveWindow;
+    property ChildWindowCount: integer read GetChildWindowCount;
+  end;
+
+
+  TfpgMDIChildForm = class(TfpgWidget)
+  private
+    {@VFD_HEAD_BEGIN: MDIChildForm}
+    Panel1: TfpgPanel;
+    bevLeft: TfpgBevel;
+    Bevel2: TfpgBevel;
+    bevBottom: TfpgBevel;
+    Bevel4: TfpgBevel;
+    bevRight: TfpgBevel;
+    Button1: TfpgButton;
+    Button2: TfpgButton;
+    Button3: TfpgButton;
+    Button4: TfpgButton;
+    bvlClientArea: TfpgBevel;
+    {@VFD_HEAD_END: MDIChildForm}
+    FMDIWorkArea: TfpgMDIWorkArea;
+    FWindowTitle: TfpgString;
+    FIsMouseDown: boolean;
+    FLastPos: TPoint;
+    FActive: boolean;
+    FOnMove: TfpgMDIChildMoveEvent;
+    procedure SetWindowTitle(AValue: TfpgString); reintroduce;
+    procedure TitleMouseMove(Sender: TObject; AShift: TShiftState; const AMousePos: TPoint);
+    procedure TitleMouseUp(Sender: TObject; AButton: TMouseButton; AShift: TShiftState; const AMousePos: TPoint);
+    procedure TitleMouseDown(Sender: TObject; AButton: TMouseButton; AShift: TShiftState; const AMousePos: TPoint);
+    procedure TitleMouseExit(Sender: TObject);
+    procedure CloseMDIWindowClicked(Sender: TObject);
+    procedure SetActive(AValue: boolean);
+    procedure ChildFormResized(Sender: TObject);
+    procedure DoOnMove(const x, y: TfpgCoord);
+  protected
+    procedure HandleMove(x, y: TfpgCoord); override;
+    property Active: boolean read FActive write SetActive;
+  public
+    constructor Create(AOwner: TfpgMDIWorkArea); reintroduce;
+    property WindowTitle: TfpgString read FWindowTitle write SetWindowTitle;
+    procedure SetClientFrame(AFrame: TfpgFrame);
+    procedure UpdateWindowTitle;
+    procedure Close;
+  published
+    property OnMove: TfpgMDIChildMoveEvent read FOnMove write FOnMove;
+  end;
 
 implementation
 
 uses
-	dbugintf;
+  dbugintf;
 
 { TfpgMDIChildForm }
 
 procedure TfpgMDIChildForm.TitleMouseMove(Sender: TObject; AShift: TShiftState;
-	const AMousePos: TPoint);
+  const AMousePos: TPoint);
 var
   dx, dy: integer;
   pt: TPoint;
 begin
-	pt := WindowToScreen(self, AMousePos);
-	if not FIsMouseDown then
-	begin
-		FLastPos := pt;
-		Exit;
-	end;
-
-	dx := pt.X - FLastPos.X;
-	dy := pt.Y - FLastPos.Y;
-	Left := Left + dx;
-	Top := Top + dy;
-	FLastPos := pt;
-	UpdateWindowPosition;
+  pt := WindowToScreen(self, AMousePos);
+  if not FIsMouseDown then
+  begin
+    FLastPos := pt;
+    Exit;
+  end;
+
+  dx := pt.X - FLastPos.X;
+  dy := pt.Y - FLastPos.Y;
+  Left := Left + dx;
+  Top := Top + dy;
+  FLastPos := pt;
+  UpdateWindowPosition;
 end;
 
 procedure TfpgMDIChildForm.TitleMouseUp(Sender: TObject; AButton: TMouseButton;
-	AShift: TShiftState; const AMousePos: TPoint);
+  AShift: TShiftState; const AMousePos: TPoint);
 begin
-	FIsMouseDown := False;
-	Panel1.ReleaseMouse;
+  FIsMouseDown := False;
+  Panel1.ReleaseMouse;
 end;
 
 procedure TfpgMDIChildForm.TitleMouseDown(Sender: TObject; AButton: TMouseButton;
-	AShift: TShiftState; const AMousePos: TPoint);
+  AShift: TShiftState; const AMousePos: TPoint);
 begin
-	FMDIWorkArea.ActiveWindow := self;
-	FIsMouseDown := True;
-	FLastPos := Panel1.WindowToScreen(self, AMousePos);
-	Panel1.CaptureMouse;
+  FMDIWorkArea.ActiveWindow := self;
+  FIsMouseDown := True;
+  FLastPos := Panel1.WindowToScreen(self, AMousePos);
+  Panel1.CaptureMouse;
 end;
 
 procedure TfpgMDIChildForm.TitleMouseExit(Sender: TObject);
 begin
-//	FIsMouseDown := False;
+//  FIsMouseDown := False;
 end;
 
 procedure TfpgMDIChildForm.CloseMDIWindowClicked(Sender: TObject);
 begin
-	Close;
+  Close;
 end;
 
 procedure TfpgMDIChildForm.SetActive(AValue: boolean);
 begin
-	if FActive = AValue then
-		Exit;
-	FActive := AValue;
-	if FActive then
-	begin
-		Panel1.BackgroundColor := clNavy;
-		bevLeft.BackgroundColor := clNavy;
-		bevBottom.BackgroundColor := clNavy;
-		bevRight.BackgroundColor := clNavy;
-		Bevel2.BackgroundColor := clNavy;
-		Bevel4.BackgroundColor := clNavy;
-	end
-	else
-	begin
-		Panel1.BackgroundColor := clMedGray;
-		bevLeft.BackgroundColor := clMedGray;
-		bevBottom.BackgroundColor := clMedGray;
-		bevRight.BackgroundColor := clMedGray;
-		Bevel2.BackgroundColor := clMedGray;
-		Bevel4.BackgroundColor := clMedGray;
-	end;
+  if FActive = AValue then
+    Exit;
+  FActive := AValue;
+  if FActive then
+  begin
+    Panel1.BackgroundColor := clNavy;
+    bevLeft.BackgroundColor := clNavy;
+    bevBottom.BackgroundColor := clNavy;
+    bevRight.BackgroundColor := clNavy;
+    Bevel2.BackgroundColor := clNavy;
+    Bevel4.BackgroundColor := clNavy;
+  end
+  else
+  begin
+    Panel1.BackgroundColor := clMedGray;
+    bevLeft.BackgroundColor := clMedGray;
+    bevBottom.BackgroundColor := clMedGray;
+    bevRight.BackgroundColor := clMedGray;
+    Bevel2.BackgroundColor := clMedGray;
+    Bevel4.BackgroundColor := clMedGray;
+  end;
+end;
+
+procedure TfpgMDIChildForm.ChildFormResized(Sender: TObject);
+begin
+  SendDebug('ChildFormResize');
+end;
+
+procedure TfpgMDIChildForm.DoOnMove(const x, y: TfpgCoord);
+var
+  rec: TfpgMoveEventRec;
+begin
+  if Assigned(FOnMove) then
+  begin
+    rec.Sender := self;
+    rec.x := x;
+    rec.y := y;
+    FOnMove(self, rec);
+  end;
+end;
+
+procedure TfpgMDIChildForm.HandleMove(x, y: TfpgCoord);
+begin
+  inherited HandleMove(x, y);
+  DoOnMove(x, y);
 end;
 
 procedure TfpgMDIChildForm.SetWindowTitle(AValue: TfpgString);
 begin
-	if FWindowTitle = AValue then
-		Exit;
-	FWindowTitle := AValue;
-	if not (csLoading in ComponentState) then
-		Panel1.Text := FWindowTitle;
+  if FWindowTitle = AValue then
+    Exit;
+  FWindowTitle := AValue;
+  if not (csLoading in ComponentState) then
+    Panel1.Text := FWindowTitle;
 end;
 
 constructor TfpgMDIChildForm.Create(AOwner: TfpgMDIWorkArea);
 begin
-	inherited Create(AOwner);
-	FMDIWorkArea := AOwner;
-	FIsMouseDown := False;
-	FLastPos := Point(0,0);
-	{@VFD_BODY_BEGIN: MDIChildForm}
-	Name := 'MDIChildForm';
-	SetPosition(369, 166, 300, 250);
-	WindowTitle := 'ChildForm1';
-	Hint := '';
-
-	Panel1 := TfpgPanel.Create(self);
-	with Panel1 do
-	begin
-		Name := 'Panel1';
-		SetPosition(0, 0, 301, 24);
-		Anchors := [anLeft,anRight,anTop];
-		BackgroundColor := TfpgColor($0A0081);
-		FontDesc := '#Label2';
-		Hint := '';
-		Text := 'Window Title';
-		TextColor := TfpgColor($FFFFFF);
-		OnMouseDown := @TitleMouseDown;
-		OnMouseUp := @TitleMouseUp;
-		OnMouseMove := @TitleMouseMove;
-		OnMouseExit  := @TitleMouseExit;
-	end;
-
-	bevLeft := TfpgBevel.Create(self);
-	with bevLeft do
-	begin
-		Name := 'bevLeft';
-		SetPosition(0, 24, 3, 211);
-		Anchors := [anLeft,anTop,anBottom];
-		BackgroundColor := TfpgColor($000080);
-		Hint := '';
-		Shape := bsSpacer;
-	end;
-
-	Bevel2 := TfpgBevel.Create(self);
-	with Bevel2 do
-	begin
-		Name := 'Bevel2';
-		SetPosition(0, 235, 16, 16);
-		Anchors := [anLeft,anBottom];
-		BackgroundColor := TfpgColor($000080);
-		Hint := '';
-	end;
-
-	bevBottom := TfpgBevel.Create(self);
-	with bevBottom do
-	begin
-		Name := 'bevBottom';
-		SetPosition(16, 248, 269, 3);
-		Anchors := [anLeft,anRight,anBottom];
-		BackgroundColor := TfpgColor($000080);
-		Hint := '';
-		Shape := bsSpacer;
-	end;
-
-	Bevel4 := TfpgBevel.Create(self);
-	with Bevel4 do
-	begin
-		Name := 'Bevel4';
-		SetPosition(285, 235, 16, 16);
-		Anchors := [anRight,anBottom];
-		BackgroundColor := TfpgColor($000080);
-		Hint := '';
-	end;
-
-	bevRight := TfpgBevel.Create(self);
-	with bevRight do
-	begin
-		Name := 'bevRight';
-		SetPosition(297, 24, 3, 211);
-		Anchors := [anRight,anTop,anBottom];
-		BackgroundColor := TfpgColor($000080);
-		Hint := '';
-		Shape := bsSpacer;
-	end;
-
-	Button1 := TfpgButton.Create(Panel1);
-	with Button1 do
-	begin
-		Name := 'Button1';
-		SetPosition(3, 4, 16, 16);
-		Text := '-';
-		Embedded := True;
-		FontDesc := '#Grid';
-		Hint := '';
-		ImageName := '';
-		TabOrder := 1;
-		TextColor := TfpgColor($000000);
-	end;
-
-	Button2 := TfpgButton.Create(Panel1);
-	with Button2 do
-	begin
-		Name := 'Button2';
-		SetPosition(251, 4, 16, 16);
-		Anchors := [anRight,anTop];
-		Text := '_';
-		Embedded := True;
-		FontDesc := '#Grid';
-		Hint := '';
-		ImageName := '';
-		TabOrder := 1;
-		TextColor := TfpgColor($000000);
-	end;
-
-	Button3 := TfpgButton.Create(Panel1);
-	with Button3 do
-	begin
-		Name := 'Button3';
-		SetPosition(267, 4, 16, 16);
-		Anchors := [anRight,anTop];
-		Text := 'o';
-		Embedded := True;
-		FontDesc := '#Grid';
-		Hint := '';
-		ImageName := '';
-		TabOrder := 1;
-		TextColor := TfpgColor($000000);
-	end;
-
-	Button4 := TfpgButton.Create(Panel1);
-	with Button4 do
-	begin
-		Name := 'Button4';
-		SetPosition(283, 4, 16, 16);
-		Anchors := [anRight,anTop];
-		Text := 'X';
-		Embedded := True;
-		FontDesc := '#Grid';
-		Hint := '';
-		ImageName := '';
-		TabOrder := 1;
-		TextColor := TfpgColor($000000);
-		OnClick := @CloseMDIWindowClicked;
-	end;
-
-	bvlClientArea := TfpgBevel.Create(self);
-	with bvlClientArea do
-	begin
-		Name := 'bvlClientArea';
-		SetPosition(2, 24, 296, 224);
-		Anchors := [anLeft,anRight,anTop,anBottom];
-		Hint := '';
-		Shape := bsSpacer;
-	end;
-
-	{@VFD_BODY_END: MDIChildForm}
-	Name := 'MDIChildForm' + IntToStr(Random(MaxInt));
+  inherited Create(AOwner);
+  FMDIWorkArea := AOwner;
+  FIsMouseDown := False;
+  FLastPos := Point(0,0);
+  {@VFD_BODY_BEGIN: MDIChildForm}
+  Name := 'MDIChildForm';
+  SetPosition(10, 10, 300, 250);
+  WindowTitle := 'ChildForm1';
+  Hint := '';
+  OnResize := @ChildFormResized;
+
+  Panel1 := TfpgPanel.Create(self);
+  with Panel1 do
+  begin
+    Name := 'Panel1';
+    SetPosition(0, 0, 301, 24);
+    Anchors := [anLeft,anRight,anTop];
+    BackgroundColor := TfpgColor($0A0081);
+    FontDesc := '#Label2';
+    Hint := '';
+    Text := 'Window Title';
+    TextColor := TfpgColor($FFFFFF);
+    OnMouseDown := @TitleMouseDown;
+    OnMouseUp := @TitleMouseUp;
+    OnMouseMove := @TitleMouseMove;
+    OnMouseExit  := @TitleMouseExit;
+  end;
+
+  bevLeft := TfpgBevel.Create(self);
+  with bevLeft do
+  begin
+    Name := 'bevLeft';
+    SetPosition(0, 24, 3, 211);
+    Anchors := [anLeft,anTop,anBottom];
+    BackgroundColor := TfpgColor($000080);
+    Hint := '';
+    Shape := bsSpacer;
+  end;
+
+  Bevel2 := TfpgBevel.Create(self);
+  with Bevel2 do
+  begin
+    Name := 'Bevel2';
+    SetPosition(0, 235, 16, 16);
+    Anchors := [anLeft,anBottom];
+    BackgroundColor := TfpgColor($000080);
+    Hint := '';
+  end;
+
+  bevBottom := TfpgBevel.Create(self);
+  with bevBottom do
+  begin
+    Name := 'bevBottom';
+    SetPosition(16, 248, 269, 3);
+    Anchors := [anLeft,anRight,anBottom];
+    BackgroundColor := TfpgColor($000080);
+    Hint := '';
+    Shape := bsSpacer;
+  end;
+
+  Bevel4 := TfpgBevel.Create(self);
+  with Bevel4 do
+  begin
+    Name := 'Bevel4';
+    SetPosition(285, 235, 16, 16);
+    Anchors := [anRight,anBottom];
+    BackgroundColor := TfpgColor($000080);
+    Hint := '';
+  end;
+
+  bevRight := TfpgBevel.Create(self);
+  with bevRight do
+  begin
+    Name := 'bevRight';
+    SetPosition(297, 24, 3, 211);
+    Anchors := [anRight,anTop,anBottom];
+    BackgroundColor := TfpgColor($000080);
+    Hint := '';
+    Shape := bsSpacer;
+  end;
+
+  Button1 := TfpgButton.Create(Panel1);
+  with Button1 do
+  begin
+    Name := 'Button1';
+    SetPosition(3, 4, 16, 16);
+    Text := '-';
+    Embedded := True;
+    FontDesc := '#Grid';
+    Hint := '';
+    ImageName := '';
+    TabOrder := 1;
+    TextColor := TfpgColor($000000);
+  end;
+
+  Button2 := TfpgButton.Create(Panel1);
+  with Button2 do
+  begin
+    Name := 'Button2';
+    SetPosition(251, 4, 16, 16);
+    Anchors := [anRight,anTop];
+    Text := '_';
+    Embedded := True;
+    FontDesc := '#Grid';
+    Hint := '';
+    ImageName := '';
+    TabOrder := 1;
+    TextColor := TfpgColor($000000);
+  end;
+
+  Button3 := TfpgButton.Create(Panel1);
+  with Button3 do
+  begin
+    Name := 'Button3';
+    SetPosition(267, 4, 16, 16);
+    Anchors := [anRight,anTop];
+    Text := 'o';
+    Embedded := True;
+    FontDesc := '#Grid';
+    Hint := '';
+    ImageName := '';
+    TabOrder := 1;
+    TextColor := TfpgColor($000000);
+  end;
+
+  Button4 := TfpgButton.Create(Panel1);
+  with Button4 do
+  begin
+    Name := 'Button4';
+    SetPosition(283, 4, 16, 16);
+    Anchors := [anRight,anTop];
+    Text := 'X';
+    Embedded := True;
+    FontDesc := '#Grid';
+    Hint := '';
+    ImageName := '';
+    TabOrder := 1;
+    TextColor := TfpgColor($000000);
+    OnClick := @CloseMDIWindowClicked;
+  end;
+
+  bvlClientArea := TfpgBevel.Create(self);
+  with bvlClientArea do
+  begin
+    Name := 'bvlClientArea';
+    SetPosition(2, 24, 296, 224);
+    Anchors := [anLeft,anRight,anTop,anBottom];
+    Hint := '';
+    Shape := bsSpacer;
+  end;
+
+  {@VFD_BODY_END: MDIChildForm}
+  Name := 'MDIChildForm' + IntToStr(Random(MaxInt));
 end;
 
 procedure TfpgMDIChildForm.SetClientFrame(AFrame: TfpgFrame);
 begin
-//	AFrame.Owner := bvlClientArea;
-	AFrame.Align := alClient;
-	AFrame.Visible := True;
-	UpdateWindowTitle;
+//  AFrame.Owner := bvlClientArea;
+  AFrame.Align := alClient;
+  AFrame.Visible := True;
+  UpdateWindowTitle;
 end;
 
 procedure TfpgMDIChildForm.UpdateWindowTitle;
 begin
-	Panel1.Text := FWindowTitle;
+  Panel1.Text := FWindowTitle;
 end;
 
 procedure TfpgMDIChildForm.Close;
 begin
-	// We can't free ourselves, somebody else needs to do it
-	fpgPostMessage(Self, FMDIWorkArea, FPGM_FREEME);
+  // We can't free ourselves, somebody else needs to do it
+  fpgPostMessage(Self, FMDIWorkArea, FPGM_FREEME);
 end;
 
 { TfpgMDIWorkArea }
 
 procedure TfpgMDIWorkArea.InternalMsgFreeMe(var msg: TfpgMessageRec);
 var
-	i: integer;
+  i: integer;
 begin
-	if Assigned(msg.Sender) then
-	begin
-		if csDestroying in TComponent(msg.Sender).ComponentState then
-			Exit;
-		RemoveComponent(TfpgMDIChildForm(msg.Sender));
-		i := FList.IndexOf(TfpgMDIChildForm(msg.Sender));
-		if i = -1 then
-			raise Exception.Create('Could not find MDI Child Form');
-		FList.Delete(i);
-		if FList.Count >= i+1 then
-			{ set focus to next child window after the one just deleted }
-			ActiveWidget := TfpgMDIChildForm(FList.Items[i])
-		else if FList.Count > 0 then
-			{ fallback to the first child window we created }
-			ActiveWidget := TfpgMDIChildForm(FList.Items[0])
-		else
-			{ there simply isn't any more child windows }
-			ActiveWidget := nil;
-		TfpgMDIChildForm(msg.Sender).Free;
-	end;
+  if Assigned(msg.Sender) then
+  begin
+    if csDestroying in TComponent(msg.Sender).ComponentState then
+      Exit;
+    RemoveComponent(TfpgMDIChildForm(msg.Sender));
+    i := FList.IndexOf(TfpgMDIChildForm(msg.Sender));
+    if i = -1 then
+      raise Exception.Create('Could not find MDI Child Form');
+    FList.Delete(i);
+    if FList.Count >= i+1 then
+      { set focus to next child window after the one just deleted }
+      ActiveWidget := TfpgMDIChildForm(FList.Items[i])
+    else if FList.Count > 0 then
+      { fallback to the first child window we created }
+      ActiveWidget := TfpgMDIChildForm(FList.Items[0])
+    else
+      { there simply isn't any more child windows }
+      ActiveWidget := nil;
+    TfpgMDIChildForm(msg.Sender).Free;
+  end;
 end;
 
 procedure TfpgMDIWorkArea.SetActiveWindow(AValue: TfpgMDIChildForm);
@@ -367,71 +408,186 @@ var
   i: integer;
   w: TfpgMDIChildForm;
 begin
-	if FActiveWindow = AValue then
-		Exit;
-	FActiveWindow := AValue;
-	FActiveWindow.BringToFront;
-	ActiveWidget := FActiveWindow;
-	for i := 0 to FList.Count-1 do
-	begin
-		w := TfpgMDIChildForm(FList[i]);
-		w.Active := (w = AValue);
-	end;
+  if FActiveWindow = AValue then
+    Exit;
+  FActiveWindow := AValue;
+  FActiveWindow.BringToFront;
+  ActiveWidget := FActiveWindow;
+  for i := 0 to FList.Count-1 do
+  begin
+    w := TfpgMDIChildForm(FList[i]);
+    w.Active := (w = AValue);
+  end;
 end;
 
 function TfpgMDIWorkArea.GetChildWindowCount: integer;
 begin
-	Result := FList.Count;
+  Result := FList.Count;
+end;
+
+procedure TfpgMDIWorkArea.MDIChildMoved(Sender: TObject; const rec: TfpgMoveEventRec);
+var
+  w: integer;
+begin
+  if FScrollingHorizonal then
+    Exit; // We are using the scrollbar to slide windows in/out of view
+  w := CalcVirtualWidth;
+  if w > Width then
+  begin
+    FHorBar.Max := w - Width;
+    FHorBar.SliderSize := Width / w;
+    if not FHorBar.Visible then
+    begin
+      FHorBar.Position := 0;
+      FLastHorizonalPos := 0;
+      FHorBar.Visible := True
+    end
+    else
+      FHorBar.RepaintSlider;
+  end
+  else
+    FHorBar.Visible := False;
+end;
+
+function TfpgMDIWorkArea.CalcVirtualWidth: integer;
+var
+  w: integer;
+  i: integer;
+  c: TfpgMDIChildForm;
+begin
+  w := Width;
+  for i := 0 to ComponentCount -1 do
+  begin
+    if Components[i] is TfpgScrollBar then
+      continue;
+    if Components[i] is TfpgMDIChildForm then
+    begin
+      c := Components[i] as TfpgMDIChildForm;
+      if c.Left < 0 then
+        w := Width + Abs(c.Left);
+      if c.Right > w then
+       w := c.Right;
+    end;
+  end;
+  Result := w;
+end;
+
+procedure TfpgMDIWorkArea.HorizontalScrollBarScrolled(Sender: TObject; position: integer);
+var
+  w: integer;
+  i: integer;
+  c: TfpgMDIChildForm;
+begin
+  FScrollingHorizonal := True;
+  for i := 0 to ComponentCount -1 do
+  begin
+    if Components[i] is TfpgScrollBar then
+      continue;
+    if Components[i] is TfpgMDIChildForm then
+    begin
+      c := Components[i] as TfpgMDIChildForm;
+      c.Left := c.Left + (FLastHorizonalPos - position);
+      c.UpdateWindowPosition;
+      fpgApplication.ProcessMessages;
+    end;
+  end;
+  FLastHorizonalPos := position;
+  FScrollingHorizonal := False;
 end;
 
 procedure TfpgMDIWorkArea.HandlePaint;
 begin
-	inherited HandlePaint;
-	Canvas.Clear(clLtGray);
+  inherited HandlePaint;
+  Canvas.Clear(clLtGray);
+end;
+
+procedure TfpgMDIWorkArea.HandleResize(AWidth, AHeight: TfpgCoord);
+var
+  rec: TfpgMoveEventRec;
+begin
+  inherited HandleResize(AWidth, AHeight);
+  if ComponentCount > 2 then
+    MDIChildMoved(self, rec);
 end;
 
 procedure TfpgMDIWorkArea.PositionScrollBars;
 begin
-	FHorBar.Left := Left;
-	FHorBar.Top := Height - FHorBar.Height;
-	FHorBar.Width := Width;
-	FHorBar.Anchors := [anLeft, anBottom, anRight];
-	FVerBar.Left := Width - FVerBar.Width;
-	FVerBar.Top := 0;
-	FVerBar.Height := Height;
-	FVerBar.Anchors := [anRight, anTop, anBottom];
+  FHorBar.Left := Left;
+  FHorBar.Top := Height - FHorBar.Height;
+  FHorBar.Width := Width;
+  FHorBar.Anchors := [anLeft, anBottom, anRight];
+  FVerBar.Left := Width - FVerBar.Width;
+  FVerBar.Top := 0;
+  FVerBar.Height := Height;
+  FVerBar.Anchors := [anRight, anTop, anBottom];
 end;
 
 constructor TfpgMDIWorkArea.Create(AOwner: TComponent);
 begin
-	inherited Create(AOwner);
-	FIsContainer := True;
-	FHorBar := TfpgScrollbar.Create(self);
-	FHorBar.Visible := False;
-	FHorBar.Orientation := orHorizontal;
-	FVerBar := TfpgScrollbar.Create(self);
-	FVerBar.Visible := False;
-	FVerBar.Orientation := orVertical;
-	PositionScrollBars;
-	FList := TList.Create;
-	FActiveWindow := nil;
+  inherited Create(AOwner);
+  FIsContainer := True;
+  FScrollingHorizonal := False;
+
+  FHorBar := TfpgScrollbar.Create(self);
+  FHorBar.Visible := False;
+  FHorBar.Orientation := orHorizontal;
+  FHorBar.OnScroll := @HorizontalScrollBarScrolled;
+
+  FVerBar := TfpgScrollbar.Create(self);
+  FVerBar.Visible := False;
+  FVerBar.Orientation := orVertical;
+
+  PositionScrollBars;
+
+  FList := TList.Create;
+  FActiveWindow := nil;
 end;
 
 destructor TfpgMDIWorkArea.Destroy;
 begin
-	FList.Free;
-	inherited Destroy;
+  FList.Free;
+  inherited Destroy;
 end;
 
 function TfpgMDIWorkArea.AddWindow(AWindowClass: TfpgFrameClass): TfpgFrame;
 var
-	frm: TfpgMDIChildForm;
+  frm: TfpgMDIChildForm;
+begin
+  frm := TfpgMDIChildForm.Create(self);
+  Result := AWindowClass.Create(frm.bvlClientArea);
+  frm.SetClientFrame(Result);
+  frm.OnMove := @MDIChildMoved;
+  FList.Add(frm);
+  ActiveWindow := frm;
+end;
+
+procedure TfpgMDIWorkArea.CascadeWindows;
+const
+  GAP = 25;
+var
+  w: integer;
+  i: integer;
+  c: TfpgMDIChildForm;
+  x, y: integer;
 begin
-	frm := TfpgMDIChildForm.Create(self);
-	Result := AWindowClass.Create(frm.bvlClientArea);
-	frm.SetClientFrame(Result);
-	FList.Add(frm);
-	ActiveWindow := frm;
+  x := 5;
+  y := 5;
+  for i := 0 to ComponentCount -1 do
+  begin
+    if Components[i] is TfpgScrollBar then
+      continue;
+    if Components[i] is TfpgMDIChildForm then
+    begin
+      c := Components[i] as TfpgMDIChildForm;
+      c.Left := x;
+      x += GAP;
+      c.Top := y;
+      y += GAP;
+      c.UpdateWindowPosition;
+      c.BringToFront;
+    end;
+  end;
+  ActiveWindow := c;
 end;
 
 end.
diff --git a/prototypes/mdi/frm_child.pas b/prototypes/mdi/frm_child.pas
index a9890a3c..acc61323 100644
--- a/prototypes/mdi/frm_child.pas
+++ b/prototypes/mdi/frm_child.pas
@@ -5,31 +5,31 @@ unit frm_child;
 interface
 
 uses
-  SysUtils, Classes, fpg_base, fpg_main, fpg_form, fpg_button, fpg_edit,
+  SysUtils, Classes, fpg_base, fpg_main, fpg_button, fpg_edit,
   fpg_checkbox, fpg_radiobutton, fpg_gauge, fpg_mdi, fpg_panel, fpg_trackbar;
 
 type
 
-	TChildForm = class(TfpgFrame)
-	private
-		{@VFD_HEAD_BEGIN: ChildForm}
-		btnClose: TfpgButton;
-		CheckBox1: TfpgCheckBox;
-		CheckBox2: TfpgCheckBox;
-		RadioButton1: TfpgRadioButton;
-		RadioButton2: TfpgRadioButton;
-		Edit1: TfpgEdit;
-		Gauge1: TfpgGauge;
-		TrackBar1: TfpgTrackBar;
-		{@VFD_HEAD_END: ChildForm}
-		FWindowTitle: TfpgString;
-		procedure btnCloseClicked(Sender: TObject);
-		procedure TrackBarChanged(Sender: TObject; APosition: integer);
-		procedure SetWindowTitle(AValue: TfpgString);
-	public
-		procedure AfterCreate; override;
-		property WindowTitle: TfpgString read FWindowTitle write SetWindowTitle;
-	end;
+  TChildForm = class(TfpgFrame)
+  private
+    {@VFD_HEAD_BEGIN: ChildForm}
+    btnClose: TfpgButton;
+    CheckBox1: TfpgCheckBox;
+    CheckBox2: TfpgCheckBox;
+    RadioButton1: TfpgRadioButton;
+    RadioButton2: TfpgRadioButton;
+    Edit1: TfpgEdit;
+    Gauge1: TfpgGauge;
+    TrackBar1: TfpgTrackBar;
+    {@VFD_HEAD_END: ChildForm}
+    FWindowTitle: TfpgString;
+    procedure btnCloseClicked(Sender: TObject);
+    procedure TrackBarChanged(Sender: TObject; APosition: integer);
+    procedure SetWindowTitle(const ATitle: TfpgString); reintroduce;
+  public
+    procedure AfterCreate; override;
+    property WindowTitle: TfpgString read FWindowTitle write SetWindowTitle;
+  end;
 
 {@VFD_NEWFORM_DECL}
 
@@ -43,126 +43,126 @@ implementation
 
 procedure TChildForm.TrackBarChanged(Sender: TObject; APosition: integer);
 begin
-	Gauge1.Progress := APosition;
+  Gauge1.Progress := APosition;
 end;
 
-procedure TChildForm.SetWindowTitle(AValue: TfpgString);
+procedure TChildForm.SetWindowTitle(const ATitle: TfpgString);
 begin
-	if FWindowTitle = AValue then
-		Exit;
-	FWindowTitle := AValue;
-	TfpgMDIChildForm(Owner.Owner).WindowTitle := FWindowTitle;
+  if FWindowTitle = ATitle then
+    Exit;
+  FWindowTitle := ATitle;
+  TfpgMDIChildForm(Owner.Owner).WindowTitle := FWindowTitle;
 end;
 
 procedure TChildForm.btnCloseClicked(Sender: TObject);
 begin
-	TfpgMDIChildForm(Owner).Close;
+  TfpgMDIChildForm(Owner).Close;
 end;
 
 procedure TChildForm.AfterCreate;
 begin
   {%region 'Auto-generated GUI code' -fold}
   {@VFD_BODY_BEGIN: ChildForm}
-	Name := 'ChildForm';
-	SetPosition(391, 210, 271, 150);
-//	WindowTitle := 'ChildForm';
-	Hint := '';
-
-	btnClose := TfpgButton.Create(self);
-	with btnClose do
-	begin
-		Name := 'btnClose';
-		SetPosition(180, 116, 80, 24);
-		Text := 'Close';
-		FontDesc := '#Label1';
-		Hint := '';
-		ImageName := '';
-		TabOrder := 1;
-		OnClick := @btnCloseClicked;
-	end;
-
-	CheckBox1 := TfpgCheckBox.Create(self);
-	with CheckBox1 do
-	begin
-		Name := 'CheckBox1';
-		SetPosition(164, 16, 120, 20);
-		FontDesc := '#Label1';
-		Hint := '';
-		TabOrder := 2;
-		Text := 'CheckBox';
-	end;
-
-	CheckBox2 := TfpgCheckBox.Create(self);
-	with CheckBox2 do
-	begin
-		Name := 'CheckBox2';
-		SetPosition(164, 36, 120, 20);
-		FontDesc := '#Label1';
-		Hint := '';
-		TabOrder := 3;
-		Text := 'CheckBox';
-	end;
-
-	RadioButton1 := TfpgRadioButton.Create(self);
-	with RadioButton1 do
-	begin
-		Name := 'RadioButton1';
-		SetPosition(164, 60, 120, 20);
-		FontDesc := '#Label1';
-		GroupIndex := 0;
-		Hint := '';
-		TabOrder := 4;
-		Text := 'RadioButton';
-	end;
-
-	RadioButton2 := TfpgRadioButton.Create(self);
-	with RadioButton2 do
-	begin
-		Name := 'RadioButton2';
-		SetPosition(164, 80, 120, 20);
-		FontDesc := '#Label1';
-		GroupIndex := 0;
-		Hint := '';
-		TabOrder := 5;
-		Text := 'RadioButton';
-	end;
-
-	Edit1 := TfpgEdit.Create(self);
-	with Edit1 do
-	begin
-		Name := 'Edit1';
-		SetPosition(8, 8, 120, 24);
-		ExtraHint := '';
-		FontDesc := '#Edit1';
-		Hint := '';
-		TabOrder := 6;
-		Text := '';
-	end;
-
-	Gauge1 := TfpgGauge.Create(self);
-	with Gauge1 do
-	begin
-		Name := 'Gauge1';
-		SetPosition(12, 44, 116, 25);
-		Color := TfpgColor($C4C4C4);
-		Hint := '';
-		Progress := 65;
-	end;
-
-	TrackBar1 := TfpgTrackBar.Create(self);
-	with TrackBar1 do
-	begin
-		Name := 'TrackBar1';
-		SetPosition(12, 84, 116, 30);
-		Hint := '';
-		TabOrder := 8;
-		Position := 65;
-		OnChange  := @TrackBarChanged;
-	end;
-
-	{@VFD_BODY_END: ChildForm}
+  Name := 'ChildForm';
+  SetPosition(391, 210, 271, 150);
+//  WindowTitle := 'ChildForm';
+  Hint := '';
+
+  btnClose := TfpgButton.Create(self);
+  with btnClose do
+  begin
+    Name := 'btnClose';
+    SetPosition(180, 116, 80, 24);
+    Text := 'Close';
+    FontDesc := '#Label1';
+    Hint := '';
+    ImageName := '';
+    TabOrder := 1;
+    OnClick := @btnCloseClicked;
+  end;
+
+  CheckBox1 := TfpgCheckBox.Create(self);
+  with CheckBox1 do
+  begin
+    Name := 'CheckBox1';
+    SetPosition(164, 16, 120, 20);
+    FontDesc := '#Label1';
+    Hint := '';
+    TabOrder := 2;
+    Text := 'CheckBox';
+  end;
+
+  CheckBox2 := TfpgCheckBox.Create(self);
+  with CheckBox2 do
+  begin
+    Name := 'CheckBox2';
+    SetPosition(164, 36, 120, 20);
+    FontDesc := '#Label1';
+    Hint := '';
+    TabOrder := 3;
+    Text := 'CheckBox';
+  end;
+
+  RadioButton1 := TfpgRadioButton.Create(self);
+  with RadioButton1 do
+  begin
+    Name := 'RadioButton1';
+    SetPosition(164, 60, 120, 20);
+    FontDesc := '#Label1';
+    GroupIndex := 0;
+    Hint := '';
+    TabOrder := 4;
+    Text := 'RadioButton';
+  end;
+
+  RadioButton2 := TfpgRadioButton.Create(self);
+  with RadioButton2 do
+  begin
+    Name := 'RadioButton2';
+    SetPosition(164, 80, 120, 20);
+    FontDesc := '#Label1';
+    GroupIndex := 0;
+    Hint := '';
+    TabOrder := 5;
+    Text := 'RadioButton';
+  end;
+
+  Edit1 := TfpgEdit.Create(self);
+  with Edit1 do
+  begin
+    Name := 'Edit1';
+    SetPosition(8, 8, 120, 24);
+    ExtraHint := '';
+    FontDesc := '#Edit1';
+    Hint := '';
+    TabOrder := 6;
+    Text := '';
+  end;
+
+  Gauge1 := TfpgGauge.Create(self);
+  with Gauge1 do
+  begin
+    Name := 'Gauge1';
+    SetPosition(12, 44, 116, 25);
+    Color := TfpgColor($C4C4C4);
+    Hint := '';
+    Progress := 65;
+  end;
+
+  TrackBar1 := TfpgTrackBar.Create(self);
+  with TrackBar1 do
+  begin
+    Name := 'TrackBar1';
+    SetPosition(12, 84, 116, 30);
+    Hint := '';
+    TabOrder := 8;
+    Position := 65;
+    OnChange  := @TrackBarChanged;
+  end;
+
+  {@VFD_BODY_END: ChildForm}
   {%endregion}
-	Name := 'ChildForm' + IntToStr(Random(MaxInt));
+  Name := 'ChildForm' + IntToStr(Random(MaxInt));
 
 end;
 
diff --git a/prototypes/mdi/project1.lpr b/prototypes/mdi/project1.lpr
index fdde8f0d..63c0882c 100644
--- a/prototypes/mdi/project1.lpr
+++ b/prototypes/mdi/project1.lpr
@@ -12,19 +12,20 @@ uses
 
 type
 
-	TMainForm = class(TfpgForm)
-	private
-		{@VFD_HEAD_BEGIN: MainForm}
-		MainBar: TfpgMenuBar;
-		MDIWorkArea: TfpgMDIWorkArea;
-		Bevel1: TfpgBevel;
-		pmChildren: TfpgPopupMenu;
-		{@VFD_HEAD_END: MainForm}
-		procedure NewFormClicked(Sender: TObject);
-		procedure miQuitClicked(Sender: TObject);
-	public
-		procedure AfterCreate; override;
-	end;
+  TMainForm = class(TfpgForm)
+  private
+    {@VFD_HEAD_BEGIN: MainForm}
+    MainBar: TfpgMenuBar;
+    MDIWorkArea: TfpgMDIWorkArea;
+    Bevel1: TfpgBevel;
+    pmChildren: TfpgPopupMenu;
+    {@VFD_HEAD_END: MainForm}
+    procedure NewFormClicked(Sender: TObject);
+    procedure miQuitClicked(Sender: TObject);
+    procedure miCascadeChildWindows(Sender: TObject);
+  public
+    procedure AfterCreate; override;
+  end;
 
 {@VFD_NEWFORM_DECL}
 
@@ -34,61 +35,69 @@ type
 
 procedure TMainForm.NewFormClicked(Sender: TObject);
 begin
-	ChildForm := MDIWorkArea.AddWindow(TChildForm) as TChildForm;
-	ChildForm.WindowTitle := Format('Child %d', [MDIWorkArea.ChildWindowCount]);
+  ChildForm := MDIWorkArea.AddWindow(TChildForm) as TChildForm;
+  ChildForm.WindowTitle := Format('Child %d', [MDIWorkArea.ChildWindowCount]);
 end;
 
 procedure TMainForm.miQuitClicked(Sender: TObject);
 begin
-	Close;
+  Close;
+end;
+
+procedure TMainForm.miCascadeChildWindows(Sender: TObject);
+begin
+  MDIWorkArea.CascadeWindows;
 end;
 
 procedure TMainForm.AfterCreate;
 begin
   {%region 'Auto-generated GUI code' -fold}
   {@VFD_BODY_BEGIN: MainForm}
-	Name := 'MainForm';
-	SetPosition(351, 159, 555, 321);
-	WindowTitle := 'fpGUI''s MDI Demo';
-	Hint := '';
-
-	MainBar := TfpgMenuBar.Create(self);
-	with MainBar do
-	begin
-		Name := 'MainBar';
-		SetPosition(0, 0, 555, 24);
-		Anchors := [anLeft,anRight,anTop];
-	end;
-
-	MDIWorkArea := TfpgMDIWorkArea.Create(self);
-	with MDIWorkArea do
-	begin
-		Name := 'MDIWorkArea';
-		SetPosition(3, 32, 548, 264);
-		Anchors := [anLeft,anRight,anTop,anBottom];
-	end;
-
-	Bevel1 := TfpgBevel.Create(self);
-	with Bevel1 do
-	begin
-		Name := 'Bevel1';
-		SetPosition(0, 300, 555, 20);
-		Anchors := [anLeft,anRight,anBottom];
-		Hint := '';
-		Style := bsLowered;
-	end;
-
-	pmChildren := TfpgPopupMenu.Create(self);
-	with pmChildren do
-	begin
-		Name := 'pmChildren';
-		SetPosition(336, 88, 120, 20);
-		AddMenuItem('Add child', '', @NewFormClicked);
-		AddMenuItem('-', '', nil);
-		AddMenuItem('Quit', '', @miQuitClicked);
-	end;
-
-	{@VFD_BODY_END: MainForm}
+  Name := 'MainForm';
+  SetPosition(351, 159, 555, 360);
+  WindowTitle := 'fpGUI''s MDI Demo';
+  Hint := '';
+
+  MainBar := TfpgMenuBar.Create(self);
+  with MainBar do
+  begin
+    Name := 'MainBar';
+    SetPosition(0, 0, 555, 24);
+    Anchors := [anLeft,anRight,anTop];
+  end;
+
+  MDIWorkArea := TfpgMDIWorkArea.Create(self);
+  with MDIWorkArea do
+  begin
+    Name := 'MDIWorkArea';
+    SetPosition(3, 32, 548, 303);
+    Anchors := [anLeft,anRight,anTop,anBottom];
+  end;
+
+  Bevel1 := TfpgBevel.Create(self);
+  with Bevel1 do
+  begin
+    Name := 'Bevel1';
+    SetPosition(0, 339, 555, 20);
+    Anchors := [anLeft,anRight,anBottom];
+    Hint := '';
+    Style := bsLowered;
+  end;
+
+  pmChildren := TfpgPopupMenu.Create(self);
+  with pmChildren do
+  begin
+    Name := 'pmChildren';
+    SetPosition(336, 88, 120, 20);
+    AddMenuItem('Add child', '', @NewFormClicked);
+    AddSeparator;
+    AddMenuItem('Cascade', '', @miCascadeChildWindows);
+    AddMenuItem('Tile', '', nil).Enabled := False;
+    AddSeparator;
+    AddMenuItem('Quit', '', @miQuitClicked);
+  end;
+
+  {@VFD_BODY_END: MainForm}
   {%endregion}
   MainBar.AddMenuItem('Children', nil).SubMenu := pmChildren;
 end;
diff --git a/src/corelib/fpg_base.pas b/src/corelib/fpg_base.pas
index 199273e2..0dda549c 100644
--- a/src/corelib/fpg_base.pas
+++ b/src/corelib/fpg_base.pas
@@ -213,6 +213,13 @@ type
   PfpgMessageRec = ^TfpgMessageRec;
 
 
+  TfpgMoveEventRec = record
+    Sender: TObject;
+    x: TfpgCoord;
+    y: TfpgCoord;
+  end;
+
+
   TfpgLineStyle = (lsSolid, lsDash, lsDot, lsDashDot, lsDashDotDot);
 
 
diff --git a/src/gui/fpg_scrollbar.pas b/src/gui/fpg_scrollbar.pas
index dd0a4c7c..440372dd 100644
--- a/src/gui/fpg_scrollbar.pas
+++ b/src/gui/fpg_scrollbar.pas
@@ -363,8 +363,6 @@ var
   area: TfpgCoord;
   mm: TfpgCoord;
 begin
-//  Canvas.BeginDraw;
-
   if SliderSize > 1 then
     SliderSize := 1;
 
@@ -436,15 +434,9 @@ begin
 
   // Paint the slider button
   if Orientation = orVertical then
-  begin
-    Canvas.DrawButtonFace(0, Width + FSliderPos, Width, FSliderLength, [btfIsEmbedded]);
-//    Canvas.EndDraw(0, Width, Width, Height - Width - Width);
-  end
+    Canvas.DrawButtonFace(0, Width + FSliderPos, Width, FSliderLength, [btfIsEmbedded])
   else
-  begin
     Canvas.DrawButtonFace(Height + FSliderPos, 0, FSliderLength, Height, [btfIsEmbedded]);
-//    Canvas.EndDraw(Height, 0, Width - Height - Height, Height);
-  end;
 end;
 
 procedure TfpgScrollBar.HandleLMouseDown(x, y: integer; shiftstate: TShiftState);