May I ask what is the programming language used to develop the Directory Opus?
It is C++.
Do I need to learn C++ in order to deal with custom settings, like add-on or script ...etc
No, not at all.
If you wanted to make a viewer plugin (e.g. to handle new picture formats) or VFS plugin (e.g. to handle new archive formats), C++ is a good choice but not the only one. But those are very advanced things which only a very small number of people do.
Scripts, toolbar commands, and general customisation do not require anything as advanced as C++.
I've never programmed before.
I know it may not sounds or seems appropriate to ask it here but in your opinion, if I want to start from scratch to learn C++ what should I do?
I think nothing better as a target or object as Directory Opus to develop for.
Grab Visual Studio Community Edition (which is free and does everything you need) and find some C++ or Win32 tutorials. I'm not sure what the good ones are these days, though; it's a long time since I learned and the old tutorials I used would not be great today, as C++ has changed a lot since then.
Browsing a site like Stack Overflow is a good idea, and you may find threads on there about good places to start, as well as lots of good questions and answers for people of all levels. CodeProject used to be a good place to go for guides and forums, and may still be; it's a while since I checked it out.
If you want to write an app like Opus or Chrome, as examples, then stick with Win32 and desktop APIs and ignore the WinRT / Metro side of Windows that was introduced in Windows 8. That new API is more modern in some ways, but I've yet to use an app written in it that didn't completely suck, and I'm guessing Microsoft will realise and admit this one day and drop it, like every other attempt they've made to replace Win32, rather than spending time improving Win32 which almost every good application still uses.
Thanks a lot brother
I owe you with a lot
Note: and this lovely forum, is it also coded or developed using C++?
Is this the forum software?
You mean it is a custom software and not general ones like phpbb or alike, right?
Or I am mistaken?
My bad, thanks a lot