The method PluginManagerPrivate::loadPlugins() is responsible for loading all plugins used by Marble. At the end of the method it is known how many plugins have been loaded. If no plugin was loaded at all, this indicates that either no plugin was installed or that the plugin path is misconfigured. To help 3rd-party developers detect this, there should be a clear warning in this case.

• At the end of the method PluginManagerPrivate::loadPlugins(), check how many plugins were loaded
• If 0 plugins were loaded, generate a warning using qWarning(). Make it verbose and give helpful hints how to resolve the situation. For example, include the plugin search paths MarbleDirs::marblePluginPath() or (if it is empty) MarbleDirs::pluginSystemPath() and MarbleDirs::pluginLocalPath().
• On Windows generate an additional warning with the same content that is shown using a QMessageBox