Hi Bernard,
Thank you for considering Aspose APIs.
Please note, Aspose.Cells.GridDesktop is a visual component to be used in .NET Forms applications in order to simulate a subset of features provided by Excel application. If you intend to use the Aspose.Cells for .NET APIs as a back-end service then you should be using the Aspose.Cells.dll in your application.
Regarding your question about applying styles on a range of cells, please review the following piece of code that demonstrates the concept in terms of Aspose.Cells for .NET API.
C#
//Create an instance of Workbook
//Optionally load an existing spreadsheet
var book = new Workbook();
//Retrieve the first Worksheet
var sheet = book.Worksheets[0];
//Retrieve the cells of first worksheet
var cells = sheet.Cells;
//Create a range of cells from A1:A10
var range = cells.CreateRange(“A1:A10”);
//Create an instance of Style & add it to styles pool
var style = book.CreateStyle();
//Set attributes for the Style object
style.Font.Name = “Arial”;
style.Font.Size = 20;
style.Font.Color = Color.White;
style.ForegroundColor = Color.Red;
style.Pattern = BackgroundType.Solid;
//Setting the line style of the top border
style.Borders[BorderType.TopBorder].LineStyle = CellBorderType.Thick;
//Setting the color of the top border
style.Borders[BorderType.TopBorder].Color = Color.Black;
//Setting the line style of the bottom border
style.Borders[BorderType.BottomBorder].LineStyle = CellBorderType.Thick;
//Setting the color of the bottom border
style.Borders[BorderType.BottomBorder].Color = Color.Black;
//Setting the line style of the left border
style.Borders[BorderType.LeftBorder].LineStyle = CellBorderType.Thick;
//Setting the color of the left border
style.Borders[BorderType.LeftBorder].Color = Color.Black;
//Setting the line style of the right border
style.Borders[BorderType.RightBorder].LineStyle = CellBorderType.Thick;
//Setting the color of the right border
style.Borders[BorderType.RightBorder].Color = Color.Black;
//Apply style onto the previously defined range
//StyleFlag decides which aspects of the new style would take effect
range.ApplyStyle(style, new StyleFlag() { All = true });
//Save the result onto disk
book.Save(dir + “output.xlsx”);
Please also note that Aspose.Cells is a pure .NET component created in managed C#, therefore concurrency and multi-threading is not a problem by any means. As long you don't have shared data source and every time a user access a new Workbook or Excel file in different thread, there will be no problem at all. However, if you have a shared data/resource or the same workbook is being accessed then you have to do the synchronization on your own.