C++ (with Qt), QML, Javascript, HTML, CSS and Clojure. Bit of a random mix, but it is working pretty well for me.
My apps desktop GUI is done in QML (Qt declarative layer) with C++ extensions (custom widgets, performance sensitive aspects, things that QML does not yet support such as drag and drop). QML supports scripting in javascript to handle events. I also use Qt's WebKit widget to display HTML/CSS/JS content (both local and from the web) and Clojure for backend logic and server code. I use quite a number of Clojure libraries for a rich environment, including some distributed/clustering stuff. My C++ app embeds a JVM which can run Clojure locally, but I have it setup so you can connect to it running on a server too (I plan to let organisations run their own servers but also host servers myself for people to make use of, perhaps as part of a subscription). I'm trying to push as much of the GUI logic to QML/JS or HTML where I can and as much of the backend logic to Clojure, but there are bits that pretty much need to be done in C++ (eg due to interop with Qt/QML). I like writing Clojure code, so I try to do as much as I can with it. I dislike Javas GUI stuff though and love QML, so the GUI is stuck in Qt/QML :)
Not quite ready to give details of what the app does just yet, though at my current rate of development I should be soon.
My apps desktop GUI is done in QML (Qt declarative layer) with C++ extensions (custom widgets, performance sensitive aspects, things that QML does not yet support such as drag and drop). QML supports scripting in javascript to handle events. I also use Qt's WebKit widget to display HTML/CSS/JS content (both local and from the web) and Clojure for backend logic and server code. I use quite a number of Clojure libraries for a rich environment, including some distributed/clustering stuff. My C++ app embeds a JVM which can run Clojure locally, but I have it setup so you can connect to it running on a server too (I plan to let organisations run their own servers but also host servers myself for people to make use of, perhaps as part of a subscription). I'm trying to push as much of the GUI logic to QML/JS or HTML where I can and as much of the backend logic to Clojure, but there are bits that pretty much need to be done in C++ (eg due to interop with Qt/QML). I like writing Clojure code, so I try to do as much as I can with it. I dislike Javas GUI stuff though and love QML, so the GUI is stuck in Qt/QML :)
Not quite ready to give details of what the app does just yet, though at my current rate of development I should be soon.