Currently, only Workbook/Worksheet could be protected. Would be nice to expose a way to protect cells for scenarios in which only particular cells should be locked for modifications.

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.

Among the other worksheet protection options, the customers can choose options like "Select locked cells" and "Select unlocked cells", enable or disable formatting options, insertion or deletion of different elements. These settings at the moment are not supported

Add API allowing change of the mouse cursor.

The formula expressions are invalidated by the formula arguments only. Which means that the formula expression will be invalidated only if some of its arguments is invalidated. But formulas like Indirect returns cell reference ranges. If something in the preferred range is changed the result have to update for which invalidation of the formula expression is needed.

The feature will be available in our official release Q1 2016.

Can we have the ability to hide the cell selector rectangle in the RadSpreadsheet? If we had this, along with the current existing functionality we would have spreadsheet capabilities inside what looks like an 'empty' page. It would be good for reporting purposes where the developer can make full use of the spreadsheet's functions but completely hide the 'spreadsheet look-and-feel' from the user.

In MS Excel, there is splitter that can be used to manually resize the formula bar. Also there is an arrow button which expands/collapses the formula bar to the last manually resized size. 

Currently indexed colors are imported only regarding the default color palette. Instead, when the entire palette is predefined using construct like:

  <colors>
    <indexedColors>
      <rgbColor rgb="00000000"/>
      ...

in styles.xml part, the indexed should be changed with the provided ones.

As this feature is not implemented, such colors are changed during the import.

It would be useful to allow the printer to be chosen directly from the Print Preview control (in the File menu in the ribbon UI). Currently the user should first press Print, and then can choose the printer in the Printer dialog, which is inconvenient.

Add API for notification when the value in a cell determined by formula is changed. This way the user can find whether by changing a cell value the result of a formula that refers to that cell value is changed.

For example:

A1: 100
A2: 5
A3: =A1+A2

When A2 is changed, the notification should be rise for A3 (as its value is also changed).

The fix is available in our latest LIB release (v. 2015.1.0323).

Implement functionality to rotate the text in a cell.

When the user clicks in the gray area of the scrollbars, the view could scroll one page at this direction, similar to what MS Excel do. 

Add support for preserving and exporting the macros in a macro-enabled workbook.

Macros are pieces of code written in Visual Basic for Applications (VBA) which are used to automate repetitive tasks in excel. The macros are part of the excel file. When a file contains a macro its extension becomes xlsm.
Spreadsheet should be able to import and export xlsm files and edit the macros in them.

This is similar to Visual Studio's IntelliSense, but appears while typing formulas in cells on in the FormulaBar.

https://support.office.com/en-us/article/Use-Formula-AutoComplete-6d13daa5-e003-4431-abab-9edef51fae6b

Allow the customers to work with Shape objects.

Add support for visualizing and editing charts.