Bart,

 

We provide a uploader.browse() function, but it will show dialog be blocked, for the Flash/Silverlight.

 

So we put a transparent layer to the button for that case.

 

You can try this way :

 

<CuteWebUI:Uploader ID="Uploader1" runat="server" InsertButtonID="MyButton">
</CuteWebUI:Uploader>
<asp:Button ID="MyButton" runat="server" Text="My Button" />
<input type=checkbox id='checkbox1' name="checkbox1" />Check It Before Browse File
<script>
function CuteWebUI_AjaxUploader_OnBrowse()
{
 //this is the example code, after the button be clicked, this function will be called

 if(!document.getElementById("checkbox1").checked)
 {
  alert("Please check the checkbox");
  //you can cancel the dialog
  return false;
 } 
}
</script>

 

Regards,
Terry