Code example in Qt Virtualkeyboard documentation suggests to use Qt.inputMethod.visible,
but for such example qmllint (dev branch) generates:

Property "visible" not found on type "QObject"

The type of Qt.inputMethod can't change, as it is in QtGui, and the Qt global object can be used without import QtQuick.  So for tooling, it's indeed only a QObject. For qmllint, we could add another custom detection though, which suggests switching to the InputMethod singleton as a fix