Other people have mentioned Qt, which is great, but I'd like to point out there it also support QML which is probably better your you.
* It is backed by Qt and rendered by OpenGL, so it performs very well.
* It has very easy syntax, especially automatic variable binding, so there is very little boilerplate for event handingl.
* It supports JavaScript. You can code the logic in either JS or C++, depending on whether you need the performance or not, and it can be easily split between the two.
* It is backed by Qt and rendered by OpenGL, so it performs very well.
* It has very easy syntax, especially automatic variable binding, so there is very little boilerplate for event handingl.
* It supports JavaScript. You can code the logic in either JS or C++, depending on whether you need the performance or not, and it can be easily split between the two.
* They actually support two sets of pre-made controls, one that looks like desktop UI (http://doc.qt.io/qt-5/qtquickcontrols-index.html) and one that looks like Android or iOS (https://doc.qt.io/qt-5/qtquickcontrols2-index.html). Or you can design your own UI from rectangles and other shape. Or combine all three.