Editable Table has additonal frames where to change?

Hi

So we patched our SAP BW NW 7.31 SPS5 to SPS8 since then we get this ugly addtional frames around every input cell.

Does anyone know where I change that in the theme editior? I'm just not able to figure out which setting that causes?

I'm talkin about the greyish incell frame

thanks

Martin