I noticed that when calling SpreadsheetGear's Factory.GetWorkbook(filename) method, that it can successfully read in the file, even if that file is currently open in Excel.
I'm guessing the method is doing something like opening a FileStream using FileShare.ReadWrite ? e.g. like:
FileStream fsSource = new FileStream(filename, FileMode.Open, FileAccess.Read, FileShare.ReadWrite)
This is overall a useful feature, but I'm wondering if there are possible edge case scenarios to be aware of ? e.g. maybe if, as the file is being read, the user saves changes to the file in Excel.