Looks like others have had this need and idea, but submitting to reiterate the need..
Would it be possible to create a button in Preferences/sync pane that would make any and all files that are declared synced to be made online-only? That is.. I've set all my Dropbox files to online-only, then, as I do my work I need to make some files Available Offline. I try to set them to online-only as soon as I'm done, but sometimes forget as I need to get on with more work, and I'll never remember at end of day. Such an "online-only reset" button would help me greatly in keeping my local storage organized. I work at a company with a photos folder that likely numbers in the thousands and thousands, I touch many each day, but have not been able to manually reset each to online only after each one I access. Many thanks for your attention!
