ExcelGrid
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Shows a class that extends the C1FlexGrid to provide Excel-like features.

This sample implements a C1FlexGridExcel class that extends the C1FlexGrid
to provide the following features:

- ColorScheme:
The C1FlexGridExcel has a ColorScheme property that allows you to select 
color schemes that match the Microsoft Office schemes: Blue, Silver, and Black.

- Row and Column Headers:
The C1FlexGridExcel has a custom CellFactory that generates labels for
the column and row headers. Column headers display letters and row headers
display the row index.

- Custom Outlines:
The C1FlexGridExcel CellFactory generates images for expanded and collapsed
nodes that look like the icons used in Excel.

- Pdf Export:
The C1FlexGridExcel uses the C1.Silverlight.Pdf assembly and the GetPageImages
method to export the grid to Pdf files.

- Xlsx Export:
The C1FlexGridExcel control uses the C1.Silverlight.Zip assembly to export the grid to 
Excel OpenXML files (xlsx).

- Undo/Redo:
The C1FlexGridExcel implements a flexible undo/redo stack.

- Enhanced filtering:
The C1FlexGridExcel control extends the standard column filtering capabilities in 
the C1FlexGrid to provide the following additional features:
- sort control
- filtered value selection in the value filter editor
- resizable editor
- Excel appearance