The TabColor is lost on import/export and setting in the code

Add support for VALUE function. VALUE converts a text string that represents a number to a number.

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

If the lookup_value parameter and lookup_vector parameters refer cells containing text values, the function returns a Not available error ("#N/A").

XIRR function returns the internal rate of return for a schedule of cash flows that is not necessarily periodic. To calculate the internal rate of return for a series of periodic cash flows, use the IRR function.

https://support.microsoft.com/en-gb/office/xirr-function-de1242ec-6477-445b-b11b-a303ad9adc9d 

The COUNT function counts the number of cells which contain numbers.

Description from Microsoft here: https://support.office.com/en-US/article/COUNT-function-A59CD7FC-B623-4D93-87A4-D23BF411294C.

Workaround: Implement such a custom function. See Custom Functions help article here: http://docs.telerik.com/devtools/document-processing/libraries/radspreadprocessing/features/formulas/custom-functions .

In Excel this can be achieved by right click on the axis, then from the context menu select "Format Axis".  Go to the "Text Options" tab and "Text Box" group and then in the "Custom angle" field insert the desired value.

The data validation is working. However, the text can't be localized by MS Excel with installed non-English language pack after import/export with SpreadProcessing. The problem is caused by an interpretation of the data validation rule as a text instead of as a formula.

When calling AutoFitWidth on single cell selections there is no issue. However, calling it on a multi-column selection the document is corrupted and repair error message is shown when opening it in Excel.

Workaround: The AutoFitWidth method may be called for each column separately. 

An invalid file is generated when the freezing panes are set and the file is opened in Excel

ArgumentException is thrown when importing documents containing empty values

Xlsx documents with global print area defined cannot be imported. Message box "The name that you entered is not valid." is shown and internally SpreadsheetNameException is thrown. 
By default, print areas are defined in the xlsx files for specific spreadsheet:
<definedName name="_xlnm.Print_Area" localSheetId="0">Sheet1!$A$1</definedName>
but this one is without localSheetId property specified.

MS Excel can import such document and even preserve the area, but do not respect it and doesn't have UI to clear it.

By OOXML specification, this attribute is optional:
<xsd:attribute name="localSheetId" type="xsd:unsignedInt" use="optional"/>

Workaround 1 (includes processing the document with MS Excel):
- Open the document in MS Excel
- Choose Formulas -> Defined names -> Named Manager
- Choose Filter -> Names with errors
- Find all Print_Area defined names and delete them
- Save the document

Workaround 2:
- Delete all print areas with OpenXML SDK


Available in LIB version: 2017.1.213

The value formula =Round(1.015, 2) returns 1.01 which is incorrect. Excel returns 1.02.

Specific documents are imported with a wrong column width which leads to a wrong preview of the cell content.

The way the RadSpreadProcessing decides if a row should be exported works slow. It iterates through all the rows in the UsedCellRange and checks if some property is set and if not, checks if some cell is set. This is slow because each row is checked one by one.

Add support for Hidden and Empty Cells options:

https://support.office.com/en-us/article/display-empty-cells-null-n-a-values-and-hidden-worksheet-data-in-a-chart-a1ee6f0c-192f-4248-abeb-9ca49cb92274

The item is closed as duplicated of https://feedback.telerik.com/Project/184/Feedback/Details/190065-spreadprocessing-implement-right-to-left-direction.

Add support for exporting Markup-Enabled file format to PDF.

When there is a defined name referring many cells with long values, the Value of the defined name is string which does not contains the values of all the referred cells and ends with "...".

Exporting documents containing two or more cell styles with the same properties, but different names cause invalid document.