wx.Net 0.5: bug in sample code? (custom grid cell renderer)

I'm new to wx.net although been using the Python version for a while.
Not sure if this is a bug or just something I've misunderstood but any
guidance welcome:

In the grid demo, there's a cell (4,4) which has a custom cell renderer
which doesn't appear to be working. The contents are "a weird looking
cell". It's based on the GridCellStringRenderer and the Draw method
looks as if it should be drawing a green ellipse either over the text or
instead of it. This doesn't happen and it appears to be ignoring the
override and using the base Draw function (i.e. that from the
StringRenderer)

To investigate further I tried various bits of code with the following
conclusions:

- cell renderers based on wxgridcellrenderer seem to override the base
functions as expected.
- in cell renderers based on wxgridcellrenderer, the wx.DC argument
doesn't appear to reference a valid object.
- cell renderers based on wxgridcellstringrenderer seem NOT to override
the base functions.

Is this a known issue? If not, can anyone send me a working custom
renderer derived from wxGridCellRenderer?

Iain




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