Introduce support for sorting columns that contain merged cells. 

Currently, the insert hyperlink dialog displayed on Ctrl+K press in the selected cell (or cell range) allows you to create a link to a webpage page, email address or place in the same document. 

Add a "Create New Document" option that allows you to create a document from the selected cell range, like in the Excel version of the Insert Hyperlink dialog. 

Add information about the selection in the SelectionChanged event arguments. 

- We need to differentiate from mouse event to keyboard event. But since the EventArgs is empty we are not able to differentiate.

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.

Add support for digital signature in the XLSX format.

Add sheet list that allows activating a sheet similar to Excel.

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.

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.

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.

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:

Introduce support for row/column reordering via the UI