The EqualToRule does not work the same way in Excel and RadSpreasheet. 

When using string values with this rule, Excel requires using quotes while in RadSpreadsheet the quotes are interpreted as part of the value.  

When Bulgarian culture is set and a document with a chart is imported, NullReferenceException is thrown.

Escape key does not close the Insert Chart dialog.

Right borders are not rendered correctly when there is no value. 

Add formula error checking like in Excel

Exporting merged columns to PDF creates unnecessary pages. The created file contains more than 8 MB in size and empty pages. It should create only one page as done in MS Excel.

Selected merged cells jump to the bottom of the selection when it goes outside the visible area.

Selecting the whole column and then opening the Charts dialog makes the app hang

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

Having more than one rule over a cell range and managing the rules through the "Manage Rules" dialog so they switch priority does nothing and the cells do not update.

Copy-Paste rules action is not translating the rule range.

The fill handle is not working with conditional formatting rules.

New rows cannot be inserted when a rule is applied over the whole column.

Reapplying rule to а different range is not being applied.

The conditional formatting rule is not applied over shifted cells when a new row or a column is inserted or removed.

Custom styles are not visible in the style gallery after importing a document.

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:

The button should always be active. 

The button:

When the Freeze Panes option is enabled and try to insert a new comment into the next cell on the left to the Freeze Panes separator the comment is deleted.