In the following example, a ListBox onDragEnter is used to determine whether or not a drop will be allowed:

function LISTBOX1_onDragEnter(nLeft, nTop, cType, cName)

     nReturn = 0       // Default is no drop

  if cType == “F”     // Test for file being dragged

     try         // (in case cName is not char)

        if file( cName )  // See if file exists

           nReturn = 1    // Drop will be allowed

        endIf

     catch ( Exception e )

        // (Ignore error)

     endTry

  endIf

return nReturn