Somehow your indentation is a bit off?

Not too happy with the naming here. The old applet just had a checkbox for "Use single button" for menu or something like that, that would also simplify the settings page a lot ;)

I *think* you can just in the ExclusiveGroup above bind to the "current" property:

Controls.ExclusiveGroup {
    id: representationGroup
    current: plasmoid.configuration.fullRepresentation ? fullRepresentationRadio : compactRepresentationRadio
}

or you could perhaps just bind "checked" in the RadioButtons

checked: plasmoid.configuration.fullRepresentation

Can you perhaps look into making it a c++ applet rather than using a private import – we somewhat try to get away from this

Perhaps base that on font size (or just units.gridUnit)

I don't think this needs to be wrapped in Component

Also, I find it pretty cool that you just use compact and full rep for that :) I would not have thought of that

var idx = Math.max(0, Math.min(buttonRepeater.count - 1, index))

(too bad there's no qBound in QML)

You could just do button.clicked() which will end up executing the onClicked below instead of duplicating the logic here

buttonData is pretty generic of a name

It's more normal to do the bounding to the right value before you emit a signal, rather than in the signal handler in QML

Otherwise your passing bad data around, which is the sort of thing that breaks later.

it shouldn't do, the panel will take the event, and re-emit a new one in the applet position

we somewhat try to get away from this

Why?

If you return here you have an unmatching begin/remove

atoms can be cached in the ctor

Turns out this is what was causing that kate->konsole crash.
I should have trusted my reviewing instead of spending some time in valgrind...

The UI is left without updating, but we've cleared m_activeMenu.
The model has the actions stored in this casted pointer, but because QQmlEngine doesn't know it's a QObject doesn't reset it. ::trigger uses the action object with now a dangling pointer.

Just remove this if statement, the for loop with no actions will do nothing anyway, so we're not saving any processing.

We can't do this!
For one thing, every 32 bit system will pad the first half of this copy with garbage.

We can either register QAction as an uncreatable QML type; or just box in QVariant<QObject*> and pass QVariant as arguments to ::trigger