The User-defined Keysym dialog box allows you to add or remove additional keysyms which are not defined in Xmanager. You can open it by clicking User-defined Keysym in the Edit menu.
Enter the keysym name which will be added in the list.Value
Enter the keysym value as a hexdecimal format.Add
Adds the keysym you entered in the Name and Value box to the list.Remove
Removes the selected keysym from the list.Close
Closes the dialog box.