A method to modify "Diablo II" so that it behaves nicely even when its tabbed txt data files are open in an Excel type application.
Bare minimum you need a hexadecimal editor and need to know how to search for and how to modify hex values using this type of software.
Recommended hex editor : ImHex
Target: SFileOpenFileEx (Storm.dll Ordinal 268).
Method : Add FILE_SHARE_WRITE (0x02) to the call to CreateFileA()
Yohann Nicolas : Finding the right ordinal to patch was quick thanks to their 1.11b fix for this issue.