I have implemented the ListDataValidationRule code to add a dropdownlist to the spreadsheet. Based on the code I can find and the searching I have conducted, it seems to be correct, however the dropdown does not appear in the control.

The dropdown list does appear in Excel when I export the file.

When the text is set using the following code, the text in a wrapped cell is overlapping.

radSpreadSheet1.ActiveWorksheet.Cells[0, 0].SetValue(@"Blocked flow; potential increase in level in  (BLANK); potential to overfill equipment; potential spill or overflow to (BLANK) 
Blocked flow; potential increase in level in  (BLANK); 
potential to overfill equipment; potential spill or overflow to(BLANK)");
radSpreadSheet1.ActiveWorksheet.Columns[0].SetWidth(new ColumnWidth(300, true));
Worksheet worksheet = radSpreadSheet1.ActiveWorksheet as Worksheet;
CellStyle cellStyle = worksheet.Workbook.Styles.Add("Wrap Style", CellStyleCategory.Custom);
cellStyle.IsWrapped = true;
CellRange cr = new CellRange(0, 0, 10, 10);
worksheet.Cells[cr].SetStyleName("Wrap Style");

Currently, the WinForms Spreadsheet doesn't have separators between the column headers:

It would be better to have separators for the headers like the WPF Spreadsheet:

The resize option available in MS Excel is:

Please add radSpreadsheet RTL support in windows version of Telerik.

Today we testing last trial version , and we see this option inside the component properties , but its not working.

Thank You.

MS Excel has this splitter functionality: 

Please refer to the attached gif file.