[Qt5] More extensive support for applications targeted at traditional desktop environments

Traditionally Qt was focused on developing rich desktop applications. With version 4 however, there was a focus shift to more simple applications which could be used on both desktop and mobile environments. This meant that many APIs mainly oriented towards desktop applications were dropped.

Although the mobile market is promising there are two sets of applications that Qt could target:

• Simple UI applications, applications which can be ran on both mobile devices and desktop computers. Qt's main selling point here is portability between the different platforms.

• Extensive UI applications, applications which are targetted at desktop usage and are less suitable for use on mobile platforms. Qt's main selling point for this case is the huge library of available APIs to use. Typical examples of such software are advanced photo and video editing tools. These are not suitable for mobile usage because they require a lot of horsepower and because they require a large screen and very precise input.

In Qt4 many APIs useful for the second category were deprecated and removed as part of Qt3Support. These APIs seemed to be unsuitable for a library that needed to support the portability for the first set of applications.

Because in the end this made Qt less attractive for desktop usage, this suggestion is about adding back (parts of) (improved versions of) such APIs and having a superset API available when developing pure desktop applications in Qt. Especially features like being able to work with the X11 window directly, which is needed for high performance desktop applications would make Qt more suitable again for the second category of applications.