creating QWidget Plugins

[high_flyer]

Ok, I think my confusion came from the fact, that I thought the plugin must somehow inherit from QObject and can't be just QWidget only

QWidget is a QObject.

class ViewPluginInterface : public QWidget // to ensure, that anyone using this interface, is creating it as a QWidget
{
    ...
};

class ViewPluginInterface : public QWidget // to ensure, that anyone using this interface, is creating it as a QWidget
{
    ...
};

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You can't do that, since then your interface is not an interface any more.