If you try to filter a column which contains a cell with applied font color and the project is run in debug mode with enabled C# exceptions, it throws ArgumentException at System.Windows.Media.ColorConverter.ConvertFrom(ITypeDescriptorContext td, CultureInfo ci, Object value). The exception is handled and the functionality is working as expected, however this may be annoying during debugging projects containing RadSpreadsheet.

When a de-DE culture is applied the 1,1 should be parsed as a number. On the other hand the 1.1 (with a dot) should be parsed as 01.Jan. Currently, both values (1,1 and 1.1) are parsed as datetime.

Decline reason: This is reproducible only if the cell was previously formatted as DateTime. In this case the separator is not taken into account which is expected. The same behavior can be observed also in Excel.

Allow the customers to work with Shape objects.

Setting the visible size property to a small number, like 10,10, will result in missing the last column right border and last row bottom border.

Fill down (Ctrl-D) is not working in a protected worksheet with an unlocked range of cells.

Spreadsheet: Add the ability to build formulas using keyboard navigation:

1. Press '=' in a cell. The cell goes into Edit Mode. 
2. Use the Keyboard arrow keys to move in any direction. The Cell reference of the focused cell is automatically entered after the '=' into the cell which is in edit mode.
3. The user can press the Control+Arrow Key to add a reference to an entire row or column of data.

When using the Fill feature through the dialog, the series are currently filled only for the cells, which are included in the selection. Introduce functionality to fill them without requiring a selection.

A custom implementation can be plugged through a custom dialog. A sample showing how to replace the default dialog with a custom one is available in the attachments of the item.

When a workbook protection is applied, changing the color of a tab in the sheet selector shouldn't be allowed.

Workaround: Remove the Tab Color item from the Items collection of the SheetSelectorContextMenu. 

Currently the following text filters are not supported in the model, filtering popup and Custom Filter dialog:
- begins with
- does not begin with
- ends with
- does not end with
- contains
- does not contain.

All of these are supported in MS Excel.

If the RadSpreadsheet is declared as a child content in the RadBusyIndicator, there isn't any tab selected as active in the SheetSelector.

Workaround: Declare the busy indicator after the RadSpreadsheet not as its child.

For example, instead of:

<telerik:RadBusyIndicator>
    <telerik:RadSpreadsheet x:Name="radSpreadsheet" />
</telerik:RadBusyIndicator>

Do:

<Grid>
    <telerik:RadSpreadsheet x:Name="radSpreadsheet" />
    <telerik:RadBusyIndicator />
</Grid>

The overlapping of SelectionFill and SelectionStroke geometries may be seen in the attached screenshot. This scenario may be reproduced with the following RadSpreadsheet instance:

<telerik:RadSpreadsheet SelectionStroke="Red" SelectionStrokeThickness="10" FillHandleSelectionStroke="Green" SelectionFill="#550000FF" />

The default set of WPF UI controls measured in infinity results in the minimal size of the control. RadSpreadsheet should behave the same. This will help users to find out what is happening while debugging.

If a workbook contains a worksheet with RowHeight bigger than 600px (SpreadsheetDefaultValues.MaxRowHeight), an exception is thrown while trying to import such a document. 

The visualization and scrolling of documents containing many merged cells (e.g. 1000) is very slow. The control becomes almost unusable when the number increases.

DataValidationRule is persisted after pasting a cell value which is copied from a cell without DataValidationRule applied. 

For example: Cell A1 has data validation rule applied. The cell A2 doesn't have. The value from cell A2 is copied to cell A1. The result is that cell A1 still has data validation, but it shouldn't.

Workaround: Import the document without using the default command

OpenFileDialog openFileDialog = new OpenFileDialog();
openFileDialog.Filter = "All Spreadsheet Files (*.txt, *.csv, *.pdf, *.xlsx)|*.txt;*.csv;*.pdf;*.xlsx|Excel Workbook (*.xlsx)|*.xlsx|CSV (Comma delimited) (*.csv)|*.csv|Text (Tab delimited) (*.txt)|*.txt|All Files (*.*)|*.*";
if (openFileDialog.ShowDialog() == true)
{
    string extension = Path.GetExtension(openFileDialog.SafeFileName);
    using (Stream input = openFileDialog.OpenFile())
    {
        Workbook workbook = WorkbookFormatProvidersManager.Import(extension, input);
        workbook.Name = openFileDialog.SafeFileName; // in the default implementation this is set after applying the document to RadSpreadsheet and triggers the event
       
        this.radSpreadsheet.Workbook = workbook;
    }
}

Currently it's not possible to disable the fill handle feature. Provide API for disabling it.

Workaround: in the attached project.

If a cell starts with number, contains text, and some values are auto-filled using this cell as base, for example with the Fill handle, the wrong Spreadsheet's autofill generator is used, and ordinal numbers are generated. Instead, the last number (if such) should be increased.

For example, if the cell value is "35'5" and the fill handle is used in order the values to next cells to be autofilled, the values are 35th, 36th and etc., instead of the correct ones which are: 35'6, 35'7,...