Qt has provided support for state machine based development since introduction of Qt State Machine Framework in Qt 4.6. With the new functionality introduced in Qt 5.8 and Qt Creator 4.2 state machine based development is now easier than ever before.
Qt 5.8 introduces fully supported Qt SCXML module that makes it easy to integrate SCXML based state machines into Qt. Previously SCXML has been imported to Qt from external tools, which is still possible. Now Qt Creator 4.2 introduces a new experimental visual state chart editor that allows creation and modification of state charts directly with Qt Creator IDE. Together with the new editor and other improvements in Qt Creator, state machine based development can be done completely within Qt Creator.
Here is a short screen cast that shows these new features in action. For demonstration purposes, the simple state machine driven example application with Qt Quick user interface Traffic Light is being recreated from scratch.
Note that the the editor is still experimental with Qt Creator 4.2 and the plugin is not loaded by default. Turn it on in Help > About Plugins (Qt Creator > About Plugins on macOS) to try it.