Add support for custom document properties (CustomDocumentProperties).

Exporting a sheet in a workbook, results in clearly narrower column widths, this doesn't appear to be a scaling issue as letters that extend outside of a cell are occluded differently from the Excel document. Also worth noting, borders adjacent to the margin area are clipped (not an issue when exporting the same PDF from excel), text padding in the cell is not the same as the Excel document, and borders disappear unexpectedly on some text cells 

Exporting empty workbook without any worksheet is not allowed according to the specification and such documents cannot be opened in Excel. Ensure the customers cannot create such documents using the API of SpreadProcessing.

Add support for TEXT function. The TEXT function allows changing the way a number appears by applying formatting to it using format codes.

TEXT(value, format_text)

A list of the supported functions is available at http://docs.telerik.com/devtools/document-processing/libraries/radspreadprocessing/features/formulas/functions 

This function can be implemented as a custom function. Check the following resources for more details on how to achieve that:

- http://docs.telerik.com/devtools/document-processing/libraries/radspreadprocessing/features/formulas/custom-functions 
- https://github.com/telerik/xaml-sdk/tree/master/Spreadsheet/WPF/CustomFunctions 

Built-in number formats are not reevaluated after changing the culture.

If shape extent is declared, the two cell anchor points for the drawing element are ignored. For example if the TwoCellAnchorElement's from and two points declare that the image should be anchored starting from cell A1to F10 and further in the drawing declaration there is defined extents element with image size values, anchor element's points are ignored. 

The Open Document Format for Office Applications (ODF), also known as OpenDocument, is an open standard file format for spreadsheets, charts, presentations, and word processing documents using ZIP-compressed[6] XML files.

The most common filename extension for spreadsheets is .ods.

A conditional formatting rule with a custom formula is lost when importing a file generated from Microsoft Excel.

If the column has a text format set and has a mixture of text and numbers, the numbers should be exported as text as well.

Support for importing and exporting WEBP images should be implemented.

Add support for structured references in tables.

SpreadProcessing: feature request to add IEnumerable<T> Interface(LINQ) implementation with CellSelection

KeyNotFoundException: when iterating cells having a disabled 'Normal font' formatting option.

XlsFormatProvider: Handle import of documents with null format strings.

Add support for "Invert if negative" property of chart data series fill.

Add API for obtaining a collection of values from CellSelection.

In some cases, horizontal bar chart cannot be loaded correctly. This leads to issue when opening the document with the RadSpreadsheet for WPF control.

When a file with a format string of the type "\m\:0.#;\m\:0.#;\m\:0.#;\m\:\ @" is imported, argument exception is thrown.

Images don't move with cells when a row/column is inserted.

Handle import of documents with invalid elements in 'x:fonts'.