How to use KeyboardStyle with InputPanel.

[mutsuyuki]

I'm trying to customize style of virtual keyborad provided by InputPanel.

According to document of KeyboardStyle,
The style type provides the style definitions that are used by the InputPanel to decorate the virtual keyboard.
But I couldn't find how to use it with InputPanel.

I also check document of InputPanel, but there is no property using KeyboardStyle.

How do I apply KeyboardStyle to InputPanel?

I tried like below, nothing happened.

InputPanel {
    id: keyboard
    z: 99
    width: parent.width

    KeyboardStyle {
        spaceKeyPanel: Component {
            Rectangle {
                color: "red"
                width: 50
                height: 50
            }
        }
    }
}