Can this control open, edit and save Excel File from Code.
Open a File from code and not in Page_Init event.

If you put a radspreadsheet inside a radtabstrip with multipage, the controls do not render properly.

In my scenario, I have a tabstrip embedded within a tabstrip, and a grid in the nested tabstrip.  That works fine.  Once you put a spreadsheet control in the multipage, the controls do not render properly. 

However, I was able to reproduce the results with the first scenario above, which is the most simple.

When I load the radspreadsheet from an excel file, the foreground color is not loaded.

A workaround is to use the Kendo Spreadsheet widget directly which imports fore color: https://demos.telerik.com/kendo-ui/spreadsheet/server-side-import-export

Repro steps 
    go to https://demos.telerik.com/aspnet-ajax/spreadsheet/examples/import-export/defaultcs.aspx
    add some text with specific fore color
    save the excel file
    import the excel file

Expected: there is no change

Actual: the fore color is not imported. Also, font size changes, but see the related item for that

The lines shifts badly after line 10 

You think you are on line 17  but the cursor is on line 16.  Very annoying bug for those using this control.  Please fix and give us an update.

Look the attached file.

A workaround is using directly the Kendo Spreadsheet widget as this will allow you to use its latest version that does not manifest this issue: https://demos.telerik.com/kendo-ui/spreadsheet/server-side-import-export

Repro steps

    Go to https://demos.telerik.com/aspnet-ajax/spreadsheet/examples/import-export/defaultcs.aspx
    Go to an empty cell
    type some text
    change its font size (e.g., to 18)
    save the file
    import the file you just saved

Expected: nothing changes

Actual: (some) cells change their height and font size, not just the cell that was edited above

If you type 15 into the font size combo box and click away, a Javascript error is thrown and the font size of the selected cell does not change. If instead you type 16 and click away, the cell changes correctly. 16 is an option in the drop-down but 15 is not.

Error message:

RadSpreadsheetScripts.js:196 Uncaught TypeError: Cannot read property 'get_text' of null


The font size combo box works correctly in the Kendo spreadsheet demo (both with the current and the 2017.1.124 Kendo version ). You can also press enter to commit your typed font size in the Kendo widget, but not in RadSpreadsheet.

Steps to reproduce:
1. Open https://demos.telerik.com/aspnet-ajax/spreadsheet/examples/overview/defaultcs.aspx
2. Click inside the font -size dropdown
3. Type 15 and click outside the SpreadSheet

Result: A JavaScript error is thrown.

Expected: https://www.screencast.com/t/bvkiEnFk7uhc (as in the Kendo Spreadsheet http://demos.telerik.com/kendo-ui/spreadsheet/index)

Actual: https://www.screencast.com/t/6Vu2f1bR3Oy0 (the tooltip is not visible) https://demos.telerik.com/aspnet-ajax/spreadsheet/examples/overview/defaultcs.aspx

Workaround: 
Add the styles for the tooltip from the Kendo Spreadsheet

html body .RadSpreadsheet .k-tooltip {               

    border-radius: 4px;
    background-image: none, linear-gradient(rgba(255, 255, 255, 0.6) 0px, rgba(255, 255, 255, 0) 100%);
    background-color: rgb(234, 232, 232);
    color: rgb(49, 49, 49);
    box-shadow: rgba(0, 0, 0, 0.3) 0px 4px 6px;
    background-position: 50% 50%;
    border-color: transparent;
    z-index: 12000;
    min-width: 20px;
    text-align: center;
    border-style: solid;
    border-width: 0px;
    padding: 5px 5px 5px 6px;
    background-repeat: repeat-x;
}

related to https://github.com/telerik/kendo-ui-core/issues/3519
workaround for rounding function is using Custom Functions http://docs.telerik.com/kendo-ui/controls/data-management/spreadsheet/custom-functions

kendo.spreadsheet.defineFunction("ROUND", function (x) {
    return Math.round(x);
}).args([
    ["x", "number"]
]);

Cell cell = new Cell() { Index = 0, Formula = "=ROUND(1.2)", Bold = true, Background = "#fef0cd", Format = "$0" };

Allow to set the filename for the radspeadsheet control when a client API SaveAs is performed e.g. MyRadSpreadsheetControl.saveAsExcel("myfilename.xlsx");