How do you handle pop-up exceptions?

A pop-up exception Handler handles the pop-up messages that come up during the execution of the script in the AUT. TO handle this type of exception we make WinRunner learn the window and also specify a handler to the exception. It could be
Default actions: WinRunner clicks the OK or Cancel button in the pop-up window, or presses Enter on the keyboard. To select a default handler, click the appropriate button in the dialog box.
User-defined handler: If you prefer, specify the name of your own handler. Click User Defined Function Name and type in a name in the User Defined Function Name box.