如何将MouseDown事件处理程序添加到控件？

I have a aspx page that contain "asp:RequiredFieldValidator" controls;Problem that is when each of "asp:RequiredFieldValidator" controls activate and show their messages; other controls in my page don't working even "CANCEL" button!!! i want to enable controls in my "NEXT" button MouseDown and then disable them at my "NEXT" button MouseUp. Thanks for any other solutions...I have a aspx page that contain "asp:RequiredFi