Elvira,
But what about Mac, Android, iPhone, etc?
We have been providing FiveLinux, FiveMac, FiveDroid, FivePhone, etc. since many years ago, and the interest about them it has been really low, what made me understand along these years, that Windows (like it or not) owns the 95% or more of the bussiness applications market, and the other platforms have very little interest for bussiness applications.
Linux users want everything for free (I am talking generally), Mac is not used for bussiness apps (most apps are multimedia, but no bussiness ones), and regarding the iPhone and Android, to me the apps should be developed using Apple and Google official development tools and using other languages is to go against the flow, because they are so different in the way that they are built, that it has very little sense to use a different approach (please review my FiveDroid development, how complex it is:
https://code.google.com/p/fivedroid/wiki/GUI_editing_with_Android_and_Harbour)
In all those products, I never wanted to use any intermediate layer, because nothing is as fast and gives you such level of control as talking directly to each GUI API.
As an example look at Java apps: they tried for many years to be a standard solution for all the different operating systems. If you review a Java app, most of the time they look really ugly, because they don't use each operating system own GUI controls. So it is a layer on top of the APIs and thats quite absurd to me as we simply don't need it.