How to prevent Gnumeric from overwriting the same file by different gnumeric instances

[Yury Dubinsky <yury dubinsky gmail com>]

Hello, 

When we click on a spreadsheet file, Gnumeric every time opens the file  in a new program instance without any checking if this file was already open. Thus, it is extremely easy to accidentally overwrite the file content. 

The most of advanced text editors warn users in case when open files are changed on the disk. Office suites, such as LibreOffice, MS Office lock open files.  

Is there anything similar in Gnumeric?  

Thanks,

 Yury