Here is a quick utility method that can be used to reset a List Box to a blank state with no columns:

// UTIL_empty_listbox If (Count parameters=1)  C_TEXT($1) // object name of Listbox to empty  C_LONGINT($a) // for loop counter  For ($a;1;LISTBOX Get number of columns(*;$1))   LISTBOX DELETE COLUMN(*;$1;1)  End for End if

If the above method is saved as UTIL_empty_listbox and you have a List Box named LBoutput, you could reset the state of the LBoutput List Box with the following line of code:

UTIL_empty_listbox("LBoutput")

This is useful, for example, when populating a List Box with the output of a SQL call and you want to reset the List Box before making another SQL call.