By default MvvmCross marshals calls like RaisePropertyChanged
onto the UI thread for the convenience of developers.
If you want to disable this on an individual object, you can call ShouldAlwaysRaiseInpcOnUserInterfaceThread(false);
for that object (this is a method call rather than a property as properties on ViewModel objects are generally reserved for INotifyPropertyChanged
use)
If you want to disable this by default on all objects then you can use Mvx.Resolve<IMvxSettings>().AlwaysRaiseInpcOnUserInterfaceThread = false;
If during testing you want to provide a mock implementation for the UI thread marshalling, then see for example the N=29 video in http://mvvmcross.blogspot.co.uk/ - with some MockDispatcher
code inside https://github.com/MvvmCross/NPlus1DaysOfMvvmCross/tree/master/N-29-TipCalcTest/TipCalcTest.Tests