Export Excel : issue with null values

Hello; 

it would be very useful to take into account the null values  (re^resented with a dash '-', during excel export. 

Let me explain : 

The dash is exported in Excel that can cause some Excel formula to crash.

     As a consequence, the user need after export to replace the '-' by blank value. And he needs to take care to replace the whole cell ! If he just replace the '-', he will transform negative values into positive values !! Very dangerous ! 

So :

             * We need an option to transform null values in blank values during the export

             * or a more general option to replace in the QlikSense pivot table, null values by a real character or blank or 0. This was possible in QlikView, but not in qliksense. We have tried with usual NULLASVALUE and others script functions without no luck.  This would be also needed for the  table widget