When you select WinPopup action with 'Customize action after creation' option checked the following window form opens up:
Figure 1: Customize WinPopUp Action
General Options
Under this group box, you see the following options:
Action Name
This is the name that you specify at the time of adding action in the 'Initial Name of the Action' field.
Action Description
Here you can add a description for the added action.
Fire for this State
Here you can select a state for which the action should be fired.
Insert Variable
Here you can select a Variable for i.e. the downtime or the Source System that you can use in your Alert-Text.
Popup Destination
Here you specify the machine on which you like to have the popup's.
Enum from Network
This function fills the combo box with what it finds in your local network. Unfortunately, this can consume some time depending on your network.
Configure the Message shown in the Popup Window
The text you are looking under this heading is customizable. There are some variables present in this message. To view details about each of the variable, see variables description.