Currently if I set column border width large, it has multiple problems:

1. it will overlay on columns next to it;
2. when copy the cell with thick border and paste somewhere else, the thick border get copied as well;
3. when select cell with thick border, the border will block part of editor;

Right now, a List based validation is strict on case, it'd be nice to have a toggle for when it is appropriate.

Use case:
My app doesn't know how many rows of data the excel spreadsheet will be prior to upload.  I've defaulted to my maximum amount of 10,000 which will be normal for some, but overkill for others.  The ability to change the number of rows/columns to accommodate the size of the sheet after loading, would be a nice addition.  

As a workaround, I'm destroying and reloading the widget instance after the initial load.

This will help doing data entry in column for scenarios like entering tax details for different years in columns and also user can keep on entering new year info in rew-row right most column.

Be able to edit an spreadsheet by several users at the same time, reflecting the changes from one user to the others and viceversa.

In Kendo UI spreadsheet when wrap cell text it currently split text in middle of word. Change so that splits on white space

Ability for spreadsheet row height to be auto set from the row contents. This is to support wrapped text.

Ability to hide a sheet in kendo spreadsheet

Ability to hover over a cell and see a tooltip

1. Save Excel workbook to folder on server (the Excel file can be re-purposed in many ways)
2. Better ways to send sheet data back to controller ... more JSON serialization options, csv, etc.

We'd need support for checkboxes columns in the new Spreadsheet control.

I would like to be able to do conditional formatting against other columns and not just the existing conditional formatting.

For example:

Column 1 = 1.2
Column 2 = 1.5

If the value of Column 2 is greater than the value of Column 1, I want the color to be green.
If the value of Column 2 is less than the value of Column 1, I want the color to be red.
If the value of Column 2 is equal to the value of Column 1, I want the color to be black.

I know it seems like a small thing, but I work with complex spreadsheets, and supporting coloured sheet tabs would really help 
Love this control.

Integration of the pivot control with the spreadsheet

Show/Hide Column & Row Header

add a double line border single or multiple cell.

Add a watermark in each worksheet.

Please support Excel formulas copy and paste to Kendo Spreadsheet.

Now is the copy only the text, not formulas.

Spreadsheet import currently handles (keeps) rich text formatting of a cell if the entire cell is formatted, such as a colored row or all bold text in cell. However, if the content of the cell is a mix of plain text and formatted text, the formatting gets dropped on import. If it is possible, it would be nice to keep rich text under this condition.

Currently the API is very much limited to what is possible in the frontend in my opinion. It would be great if you could add events like:
- A cell/range was selected
- A cell was cut/pasted/copied
- The context menu was initialized
- A row/column was added
- A row was added/deleted/hidden
- A cell's content was modified
...
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