procedure TForm1.TreeView1MouseUp(Sender: TObject; Button: TMouseButton;
 Shift: TShiftState; X, Y: Integer);
var
 HTI: TTVHitTestInfo;
 Node: TTreeNode;
begin
 Node := Nil;
 if Button = mbLeft then begin
   HTI.pt.X := X;
   HTI.pt.Y := Y;
   if TreeView_HitTest(TreeView1.Handle, HTI) <> nil then begin
     Node := TreeView1.Items.GetNode(HTI.hItem);
     if TVHT_ONITEMSTATEICON = (HTI.flags and TVHT_ONITEMSTATEICON) then begin
       //узнать состояние - TVM_GETITEM
       Caption := Node.Text + ' Changed ' + IntToStr(GetTickCount mod 1000);
     end;
   end;
 end;
end;