appcelerator-developer-relations/Template.MasterDetail — comment on commit e83ee63858bec43c87e67cf20f17da9c40d9c23a
File:  line 0
By tonylukasavage:

In Android, heavyweight windows represent Activities, which have more meaning than simply being a UI element. For this reason, they need to be handled slightly differently. If you were to attempt to reuse the windows over and over again, you will see a slight black flash when you transition between them. Creating the windows on demand makes for a smoother transition.