It's not just about development, there are numerous applications built in different toolkits which many of us use everyday. Some of these apps are closed source, so suggesting a rewrite in Qt is out of question.
Don't get me wrong, it would be awesome if we could compromise on any given toolkit, but do you honestly see any of them waving the white flag?
Meanwhile, on Windows for example, there's a standard way to write GUI apps, standardized, well-known and consistent APIs to deal with GDI's toolkit etc. It's awful to write GTK apps just as it's painful to write in pure WINAPI GDI, but GDI has the advantage of being the default, so that "native look" is consistent across most applications since the 3.1 days.
Then comes the community: we have 20+ years of GUI programming happening on Windows, most people simply stick to GDI + self-made custom controls. The outcome is a huge knowledge base that helps get anything and everything done on Windows. Here in the UNIX world over the same time period the GUI developers are spread among different toolkits, so we have many "ok" people in a dozen toolkits and few experts on each one.
> Some of these apps are closed source, so suggesting a rewrite in Qt is out of question.
Qt is LGPL. So long as you dynamically link to Qt, it doesn't matter what license your app is under. If you don't dynamically link, you lose the integration benefits anyway, so there's no downside, really (Qt is backwards compatible within each major release, so just build against the earliest version of Qt 5 your app works with).
> GDI has the advantage of being the default, so that "native look" is consistent across most applications since the 3.1 days
History means we have two defaults on Linux: Qt and GTK. Qt integrates well in a GTK desktop though, so you can just use Qt.
> Don't get me wrong, it would be awesome if we could compromise on any given toolkit, but do you honestly see any of them waving the white flag?
No doubt it will be years before everything moves over, but at this point Qt is the clear winner: it's always looked better, its licensing issues are now solved, it's the only option that has remotely decent bindings for a remotely decent language. A month or so ago there was a new release of Wx and the comments here were universally "that still exists?"; GTK will go the same way.
There are other options, there are people who really like those options, but Qt has the momentum and has the knowledge base. Just use Qt and you'll be fine, or at least you'll be no less fine that you were with GDI on windows.
Don't get me wrong, it would be awesome if we could compromise on any given toolkit, but do you honestly see any of them waving the white flag?
Meanwhile, on Windows for example, there's a standard way to write GUI apps, standardized, well-known and consistent APIs to deal with GDI's toolkit etc. It's awful to write GTK apps just as it's painful to write in pure WINAPI GDI, but GDI has the advantage of being the default, so that "native look" is consistent across most applications since the 3.1 days.
Then comes the community: we have 20+ years of GUI programming happening on Windows, most people simply stick to GDI + self-made custom controls. The outcome is a huge knowledge base that helps get anything and everything done on Windows. Here in the UNIX world over the same time period the GUI developers are spread among different toolkits, so we have many "ok" people in a dozen toolkits and few experts on each one.