{ 
  In-place ToolTips are used to display text strings for objects that have been clipped, 
  in TreeView for example. The following code has been tested only on standard ListBox. 
  Of cause you can use tips on other VCLs after appropriate modification. 
  (Only copy following code to your form1's unit file) 
} 

//------------------------------------------------------------------------------ 
//  Show in-place tooltips on ListBox 
//  Author??Joe Huang                 Email??Happyjoe@21cn.com 
// 
//------------------------------------------------------------------------------ 


unit Unit1; 

interface 

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

type 
  //Override TListBox's WinProc to get CM_MOUSELEAVE message 
  TNewListBox = class(TListBox) 
  protected 
    { Protected declarations } 
    procedure WndProc(var Message: TMessage); override; 
  end; 

type 
  TForm1 = class(TForm) 
    Button2: TButton; 
    procedure FormCreate(Sender: TObject); 
    procedure Button2Click(Sender: TObject); 
  private 
    { Private declarations } 
    GHWND: HWND; 
    TipVisable: Boolean; 
    OldIndex, CurrentIndex: Integer; 
    ti: TOOLINFO; 
    ListBox1: TListBox; 

    procedure InitListBox;   //Create ListBox1 dynamically 
    procedure CreateTipsWindow;  //Create Tooltip Window 
    procedure HideTipsWindow;    //Hide Tooltip Window 

    //WM_NOTIFY message's handler, fill Tooltip Window content 
    procedure WMNotify(var Msg: TMessage); message WM_NOTIFY; 

    procedure ListBox_MouseMove(Sender: TObject; Shift: TShiftState; X, 
      Y: Integer); 
    procedure ListBox_MouseDown(Sender: TObject; Button: TMouseButton; 
      Shift: TShiftState; X, Y: Integer); 
  public 
    { Public declarations } 
  end; 

var 
  Form1: TForm1; 

implementation 

{$R *.dfm} 

{ TNewListBox } 

procedure TNewListBox.WndProc(var Message: TMessage); 
begin 
  case Message.Msg of 
    CM_MOUSELEAVE: Form1.HideTipsWindow; 
  end; 
  inherited WndProc(Message); 
end; 

{ TForm1 } 

procedure TForm1.InitListBox; 
begin 
  ListBox1 := TNewListBox.Create(Self); 
  ListBox1.Parent := Self; 
  ListBox1.Left := 50; 
  ListBox1.Top := 50; 
  ListBox1.Width := 200; 
  ListBox1.Height := 200; 
  //append serveral items for testing 
  ListBox1.Items.Append('happyjoe'); 
  ListBox1.Items.Append('Please send me email: happyjoe@21cn.com'); 
  ListBox1.Items.Append('Delphi 5 Developer''s Guide'); 
  ListBox1.Items.Append('Delphi 5.X ADO/MTS/COM+ Advanced Development'); 

  ListBox1.OnMouseMove := ListBox_MouseMove; 
  ListBox1.OnMouseDown := ListBox_MouseDown; 
end; 

procedure TForm1.FormCreate(Sender: TObject); 
begin 
  Self.Font.Name := 'Tahoma'; 
  InitListBox; 
  CreateTipsWindow; 
end; 

procedure TForm1.CreateTipsWindow; 
var 
  iccex: tagINITCOMMONCONTROLSEX; 
begin 
  // Load the ToolTip class from the DLL. 
  iccex.dwSize := SizeOf(tagINITCOMMONCONTROLSEX); 
  iccex.dwICC := ICC_BAR_CLASSES; 
  InitCommonControlsEx(iccex); 

  // Create the ToolTip control. 
  GHWND := CreateWindow(TOOLTIPS_CLASS, '', 
                        WS_POPUP, 
                        Integer(CW_USEDEFAULT), Integer(CW_USEDEFAULT), 
                        Integer(CW_USEDEFAULT), Integer(CW_USEDEFAULT), 
                        0, 0, hInstance, 
                        nil); 

  // Prepare TOOLINFO structure for use as tracking ToolTip. 
  ti.cbSize := SizeOf(ti); 
  ti.uFlags := TTF_IDISHWND + TTF_TRACK + TTF_ABSOLUTE + TTF_TRANSPARENT; 
  ti.hwnd := Self.Handle; 
  ti.uId := ListBox1.Handle; 
  ti.hinst := hInstance; 
  ti.lpszText := LPSTR_TEXTCALLBACK; 
  ti.Rect.Left := 0; 
  ti.Rect.Top := 0; 
  ti.Rect.Bottom := 0; 
  ti.Rect.Right := 0; 

  SendMessage(GHWND, WM_SETFONT, ListBox1.Font.Handle, Integer(LongBool(False))); 
  SendMessage(GHWND,TTM_ADDTOOL,0,Integer(@ti)); 
end; 

procedure TForm1.WMNotify(var Msg: TMessage); 
var 
  phd: PHDNotify; 
  NMTTDISPINFO: PNMTTDispInfo; 
begin 
  phd := PHDNotify(Msg.lParam); 
  if phd.Hdr.hwndFrom = GHWND then 
  begin 
    if phd.Hdr.Code = TTN_NEEDTEXT then 
    begin 
      NMTTDISPINFO := PNMTTDispInfo(phd); 
      NMTTDISPINFO.lpszText := PChar(ListBox1.Items[CurrentIndex]); 
    end; 
  end; 
end; 

procedure TForm1.ListBox_MouseDown(Sender: TObject; Button: TMouseButton; 
  Shift: TShiftState; X, Y: Integer); 
begin 
  if TipVisable then     //when mouse down, hide Tooltip Window 
  begin 
    SendMessage(GHWND,TTM_TRACKACTIVATE,Integer(LongBool(False)), 0); 
    TipVisable := False; 
  end; 
end; 

procedure TForm1.ListBox_MouseMove(Sender: TObject; Shift: TShiftState; X, 
  Y: Integer); 
var 
  Index: Integer; 
  APoint: TPoint; 
  ARect: TRect; 
  ScreenRect: TRect; 
begin 
  Index := ListBox1.ItemAtPos(Point(X, Y), true); 
  if Index = -1 then 
  begin 
    SendMessage(GHWND,TTM_TRACKACTIVATE,Integer(LongBool(False)), 0); 
    OldIndex := -1; 
    TipVisable := False; 
    Exit; 
  end; 
  CurrentIndex := Index; 
  if Index = OldIndex then Exit; 
  if TipVisable then 
  begin 
    SendMessage(GHWND,TTM_TRACKACTIVATE,Integer(LongBool(False)), 0); 
    OldIndex := -1; 
    TipVisable := False; 
  end else 
  begin 
    ARect := ListBox1.ItemRect(Index); 

    if (ARect.Right - ARect.Left - 2) >= ListBox1.Canvas.TextWidth(ListBox1.Items[Index]) then 
    begin 
      OldIndex := -1; 
      Exit; 
    end; 
    APoint := ListBox1.ClientToScreen(ARect.TopLeft); 
    windows.GetClientRect(GetDesktopWindow, ScreenRect); 

    if ListBox1.Canvas.TextWidth(ListBox1.Items[Index]) + APoint.X > ScreenRect.Right then 
      APoint.X := ScreenRect.Right - ListBox1.Canvas.TextWidth(ListBox1.Items[Index]) - 5; 
    SendMessage(GHWND, 
                TTM_TRACKPOSITION, 
                0, 
                MAKELPARAM(APoint.x - 1, APoint.y - 2)); 

    SendMessage(GHWND,TTM_TRACKACTIVATE,Integer(LongBool(True)), Integer(@ti)); 
    OldIndex := Index; 
    TipVisable := True; 
  end; 
end; 

procedure TForm1.HideTipsWindow; 
begin 
  if TipVisable then 
  begin 
    SendMessage(GHWND,TTM_TRACKACTIVATE,Integer(LongBool(False)), 0); 
    OldIndex := -1; 
    TipVisable := False; 
  end; 
end; 

// Test it: 

procedure TForm1.Button2Click(Sender: TObject); 
begin 
 InitListBox; 
 CreateTipsWindow; 
end; 

end. 
end.