Examples for MuseScore 2.x Plugin Development
Shows how to use the Settings QML object from Qt.labs.settings. Setting a category is important, as it keeps your settings from colliding with other plugins/MuseScore that use the same setting name.
This plugin also shows how to dynamically popuplate a ComboBox. The caveat there is that this doesn't work for pluginType: "dialog", so you'll have to manually wrap your plugin in a Dialog and open and close it.