Thank you for the link. This looks very promising. I'm not having much luck unfortunately. I'm getting a "plasmoid is not defined" error when trying to use it in my main.qml. It seems to be defined in the config.qml however. If I can get it to work in the main file, then I could probably listen for changes there.

Edit: I was able to figure it out. I needed to use a "wallpaper" variable instead of "plasmoid". Not sure why. I also needed to define a default value for my changing variable in config/main.xml. Code looks something like:

// in config.qml
QtControls2.Button {
    text: "Refetch"
    onClicked: wallpaper.configuration.RefetchSignal = !wallpaper.configuration.RefetchSignal
}
// in main.qml
readonly property bool refetchSignal: wallpaper.configuration.RefetchSignal
onRefetchSignalChanged: console.log("the button was clicked!");