Option to set color for NaN

[sepro]

In the heatmap if have a number of missing values, which result into blanks in the pyloxml file. These are now rendered as black cells in the heatmap. Is there a way to specify the color for undefined values or could this be implemented. A complete blank area (no border) would be even better to visually distinguish between cells with and without a value.

       <values for="128431">
          <value>0.6519588984865536</value>
          <value>0.4649132014791207</value>
          <value>0.3776271345321803</value>
          <value></value>
          <value>1.0</value>
          <value></value>
        </values>

[vibbits]

solved by 3470b53