Hi,

I think it would be really cool to include a search bar in the filter window, as implemented in Excel (Please find attached a screenshot for demonstration). This is a very useful functionality, as there may be too many options to choose from is the filter is added to subject ID, which could result in thousands IDs.

To reproduce; 

- Set the language to Korean

- Type "r" in one of the cells

- Use the AutoFill functionality

At this point, FatalExecutionEngineError occurs (see attached).  

To reproduce: 

- Select some cells within the same column using Ctrl+Click

- Use the context menu to copy the cells

This works in Excel when the cells are within the same column. 

The style name "+-" is a valid one, but the StyleGallery crashes because it tries to set the name as a value of a cell and it is not a valid cell value.

Currently, this can be achieved partially by using the FlowDirection property but the result could be unexpected for right-to-left. 

Right now this functionality is missing and the user is not able to scroll the viewer when the row header is selected and not the cell.

Print Preview's "Fit All Columns on One page" does not fit columns on one page.

SUBSTITUTE  - replaces text in a given string by matching.
REPLACE - replaces characters specified by location in a given text string with another text string.

The PickCellRange dialog should allow using the formula selection to select cell ranges and convert them into text.

This feature allows automatically to group ordered data in the table and calculate the subtotals of the values column in each group of similar items. The subtotals are included just after each grouped items.

Applying a Number number format in a cell and then entering fractional number values like 1.2/2 results in cell value equal to 37258 if it is formatted as a date it will be 1/2/2002.

When entering values in the cells fast some of the values are skipped.

The SheetSelectorTabItem background is not properly applied and the text is not readable. This is easily noticeable in themes with a dark color palette. 

Currently, when the user is editing a cell and saves the document without leaving the edit mode first, the current value is not preserved in the saved document.
When pressing the File -> Save button in the ribbon, the Save dialog doesn't appear at all.
Workaround: Manually commit the change before saving. This workaround will also respect data validation:

When a user setups a page and chooses to customize the Header's Odd and Even pages, the tab headers become clipped.

When Esc key is pressed charts dialog should close.

Some of the RadSpreadsheet child controls do not apply the new theme, but stay with office black applied when theme is set on control level.

RadSpreadsheet should respect negative time values as MS Excel does it.

Returns a Range object that represents the current region. The current region is a range bounded by any combination of blank rows and blank columns. If we want to be consistent with MS Excel we should implement this property. It is useful for many operations of a region such as filtering(selecting one cell and executing the Filter command should apply it to the current region), sorting, selecting all and etc. This document will be useful: https://docs.microsoft.com/en-us/office/vba/api/excel.range.currentregion.

When the PrintPreview has to show many UIElements at once, the performance is slow.