[Qt5-feedback] C++ api to use for UI in addition to QML

[Uwe Rathmann]

As maintainer of the Qwt library ( http://qwt.sf.net ) I have a different 
point of view:

> INTERFACE COMPATIBILITY:  Sometimes, like minor dot releases.

I have no idea which Qt version is running on the system of a Qwt user - so 
the code of a Qwt release always has to work with many different Qt versions. 
Testing the code with all the different platforms, compiler versions and Qt 
versions is already hard enough.

Each Qwt application always depends on Qt and Qwt ( and maybe other 3rd party 
libraries ). In case an interface incompatible bug fix in the Qt library the 
application would have to wait until all other libraries have been adopted.

> BINARY COMPATIBILITY: Don't care.  Never care, really.

Maybe this is not such an issue for Windows people, but on Linux you have the 
concept of a distribution. For a distributor an incompatible version of a core 
library means to rebuild every depending library ( like KDE ) and every 
application using Qt. And of course each user has download all updated 
packages.

This said I would like to point the attention of the Qt development to the 
special situation of Qt addon libraries. In the past ( f.e. style sheets ) 
this seems to be not always been in the focus, when making design decisions.

Uwe