This applys to wxpython 2.8.11.0 MSW, not sure about anything else
I had a problem with the GridWithLabelRenderersMixin when using an
empty grid, it would create an exception in the _onPaintRowLabels
method, I found the problem to be on line 105 where it would loop
through the list of rows, even when there were no rows because the
method CalcRowLabelsExposed returns a list with -1 in it, and it would
try to treat -1 as a real row.
My fix was to add an extra check to see if rows != [-1]