You're hard-coding colors, this will break as soon as the style is changed.

No need to hardcode here, instead set:

color: PlasmaCore.ColorScope.backgroundColor

Same, you can set:

color: styleData.selected ? PlasmaCore.ColorScope.highlightedTextColor : PlasmaCore.ColorScope.textColor

For this label we should also add:

font.pointSize: config.fontSize

This will make sure the size of the labels is the same as the one used for the button label.

PlasmaCore.ColorScope.highlightColor

Just remove this, you would be trying to mimic the PlasmaComponents.Highlight with it, but that's not what we use in menus in the desktop.

Also, do we need this?

The extra padding makes it resemble the Breeze menus found in normal applications a bit more. (Also larger space to click on)

One more thing that I realized is missing here and that would make everything look like the desktop menus is a 1px border.

Now the stolen code should sort of look like this:

property color borderColor: PlasmaCore.ColorScope.textColor
border.color: Qt.rgba(borderColor.r, borderColor.g, borderColor.b, 0.3)
border.width: 1

Unfortunately for some reason rgba fails when using dark themes and the border just turns white. Maybe you could figure out something better, but if you get stuck it's not super important.

We still need to remove this bit of hardcoding:

color: PlasmaCore.ColorScope.highlightColor

and in the other file as well, of course.

It's still not working right with dark themes:

What do you say we steal the code for kirigami's separator color?

• first we remove the property color ... line above, and then do:

border.color: Qt.tint(PlasmaCore.ColorScope.textColor, Qt.rgba(color.r, color.g, color.b, 0.7))

looks good now IMO:

there's whitespace here

whitespace here as well

Why does this have to be QQC1?

1. Styles are a QQC1 thing (QQC2 components can't take them)
2. The PlasmaComponents.ToolButton's menu property won't accept a QQC2 menu (tried it).

AFAIK we can't style QQC2 Menus :/

There's also another non-style error that pops up.

I would suggest to consider import porting for some future date.