Currently it is impossible to share a Dropbox folder between Windows and Linux installs on the same PC. They appear to contain the same files with the same metadata, but Dropbox for Linux refuses to write to an NTFS partition, and similarly Dropbox for Windows refuses to write to ext4.
Is there a workaround for this? I don't want two copies of everything. I have been a loyal Dropbox user for years because I believe in supporting software that does one thing and does it well, but this "no mixing filesystems" rule means I have to choose between Dropbox and my dual-boot. I would love it if I didn't have to choose, and I'm sure I'm not alone!