avoid opening two pop up windows while executing an application.

Hi friends,

In my application. i had placed a gridview.In gridview, i had checkbox,bounded fileds, imagebutton.I placed a button "open" above gridview.

I need to select the checkbox,then click the open button. After clicking the open button, the corresponding document which are checked should pop up in new window.in the pop up window i placed exit button. while clicking the exit button only the 2nd document should open in same window.

 while clicking the exit button it opens the new window. i need to avoid it.

My coding here...

Btnopen_click() Event

 StringBuilder sb = new StringBuilder();
                        sb.Append("javascript:window.showModalDialog('" + "doc.aspx?dmtUrl=" + durl + "&PatientID=" + pid + " ','#1','dialogHe ...