Single Click Functionality
In general the SingleClick property of the RadToolBar control is used to avoid multiple postbacks or callbacks to the server, so that once a button is clicked, the user can not click it again until the request is completed. In general there are three values that you can set to the property. You can find a list of them below.
ToolBar: This value makes all of the buttons in the RadToolBar control inactive until the request is complete.
Button: When you set the value to Button, you will make only the clicked button inactive while the request is being executed.
None: Setting the value to None, you enable the user to click multiple times to the buttons of the control.
Note that this property is valid as of Q2 2013 SP1 release of the ASP.NET AJAX controls.