Vertical and horizontal scroll bar moves too fast once outside of the Viewport and one is dragging the selection.

 RadSpreadsheetSheetSelector add options for disabling the reordering and the editing of the sheets 

Implement auto complete for ListDataValidationRule like in Excel.

Provide a way so one can change the default cell editor with a custom one.

The sheet selector should hide sheets when their visibility is set to hidden or very hidden. The context menu of the sheet selector should contain Hide and Unhide options that allow to hide a sheet or unhide one of the hidden sheets.

Implement pasting of images similar to Excel. 

Investigate if the performance with large files can be improved. Currently a document with a million ros is opened slowly and the memory consumption is high. 

Implement functionality to rotate the text in a cell.

If a worksheet spans more than one page, you can print row and column headings or labels (also called print titles) on every page to ensure that the data is properly labeled.
Duplicate of SpreadProcessing: Repeat specific rows or columns on every printed page (telerik.com)

In Excel, when you copy a range and then paste it into a larger one, the values are repeated to fill the larger range. This can be included in RadSpreadsheet as well.

Currently, Custom IconSets are not supported when having Conditional Formatting scenarios.

One cannot reference another sheet in a formula by using the UI 

Selecting multiple columns that are not necessarily next to each other leads to incorrect chart series categories. Having the same columns next to each other and selecting all of them with single selection results in a correct chart. Make it possible for the user to make multiple selections and create charts based on them.

Spreadsheet :Export/Import of merged cells from several columns leads to - 'A' is invalid row name error

XLSB is binary format that should theoretically allow fast reading and writing to the file. 

With the current implementation, the Notes support only a rectangular shape.

Examples:

Add support for conditional formatting of cells - allow applying of rules used during visualization of cells to automatically apply formatting depending on their values.

The MergeAndCenter command binding in the SpreadsheetRibbon causes a NullReferenceException.

Introduce support for row/column reordering via the UI

Hello, 
we have an Excel export in our software that we solved via Telerik Spreadsheet. 
An exported Excel Table can also contain images. 
These pictures are inserted as shape objects. 
The Placement Property is set to xlMove (xlPlacement Enum) in Excel. 
If you now filter the data in Excel, the images remain and are not hidden. 
We therefore need a way of being able to change this Placement Property to the Value xlMoveAndSize
It would be very desirable if this option were made available in Telerik Spreadsheet as our customers urgently need it.