This is true of raw Windows APIs as well as high level runtimes like the. It's very insidious how deeply embedded this problem is. Most applications don't work with them and even if they do there may be odd behaviors caused by interaction with other applications, components or tools that don't. It's an inherent issue in Windows because the base Windows file APIs by default don't recognize these long paths. For example, Explorer won't let you create a folder name that ends up with a path that is longer than 260 characters and you can delete folders or files in folders that exceed the MAX_PATH limit. It's not just Markdown Monster - even Windows Explorer and command shells like PowerShell and Command have issues with long paths. The native Windows APIs can handle files up to the 260 character limit, but exceed that and lots of things go boom. Windows traditionally has a 260 character path limit which applies to both the folder + filename combination. I've seen file IO errors for opening files not found in my application logs, and most of these are probably caused by this very same scenario. The direct file open is one scenario, but this can come up plenty of other scenarios too - opening related assets like image files or saving a new file in a folder that has a long path. Any file opened in this path would fail with a File not found exception which would then not open the file in Markdown Monster. After a bit of back and forth, it turns out the user was trying open a file in a folder that exceeded Windows MAX_PATH limit, which is 260 characters. Odd, because if that was a wide-spread problem I'd hear about this no end, but this was a one-off bug report.
Today I got a bug report for Markdown Monster that said that Markdown files could not be opened from certain locations.