TreeViewCheckBox_Code_3

procedure TForm1.TreeView1Click(Sender: TObject);
var
 P: TPoint;
begin
 GetCursorPos(P);
 P := TreeView1.ScreenToClient(P);

 if (htOnStateIcon in TreeView1.GetHitTestInfoAt(P.X, P.Y)) or
    (htOnLabel in TreeView1.GetHitTestInfoAt(P.X, P.Y)) then
  begin
   ToggleTreeView(TreeView1.Selected, Checked, UnChecked, NotAll);
  end;
end;

procedure TForm1.TreeView1KeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
 if (Key = VK_SPACE) and Assigned(TreeView1.Selected) then
  begin
   ToggleTreeView(TreeView1.Selected, Checked, UnChecked, NotAll);
  end;
end;