"wpf how to use a converter for child bindings of multibinding?" Code Answer

there is no need to check the targettype, just check the type of value passed into convert method.

public object convert(object value, type targettype, 
                      object parameter, system.globalization.cultureinfo culture)
{
    if (!(value is bool))
        throw new invalidoperationexception("value is not bool");

    return !(bool)value;
}

By Sam Phomsopha on August 16 2022