You can use vibed:
http://vibed.org/api/vibe.core.file/DirectoryWatcher
Or just vibe-core
https://code.dlang.org/packages/vibe-core
OrĀ 
https://code.dlang.org/packages/eventcore

As a bonus you can use it for networking too.

About GUI I do not know what is the best solution. I have some experience with GTKD, which works well for me.



On Tue, Oct 9, 2018 at 7:25 PM Ephrahim via Digitalmars-d-learn <digitalmars-d-learn@puremagic.com> wrote:
Hi Everyone, i'm planning on developing a software for
synchronizing folder contents across multiple computers. The
software will evolve very quickly into virtual Remote Desktop
Access system.
So i've been considering C++ for this, its the best in the market
of all things fast at the moment (Considering the availability of
tools and docs). But i hate just two things in the language,
(.cpp + .h files) and no "easy" centralized package manager.
So i'm definitely considering D and Python now, but D seems to
satisfy my needs as per this software. I've developed very good
custom server for hardware before, and it performed very well.
So i need your help guys, can you point me to any documentation
or libraries i can use to watch files/folders for changes
(delete, edit, new content)?
I intend to make this a command line tool for a start, but i'll
need a GUI sooner or later. So i also need help pointing me to
the best available GUI library D has.

Your help will be so valuable and really appreciated sir/ma. I'll
be waiting excitedly for your responses!

Also i'm very sorry if i didn't post this to the right
Thread/Forum, i just found this forum and i wasn't very sure
where i'd post this. Thanks a lot