Hello,
there is no detailed document about the region mechanism as this is an implementation aspect of the Mosaic framework. It is just an optimization to reduce the resulting dirty area. Instead of adding all rectangular areas that have to be redrawn into one area, the Mosaic framework tries to minimize that by collecting three areas. Each time a view is invalid, its Bounds are compared with the three dirty regions and added to that region that fits best.
This is just an optimization to avoid that a few small GUI components with animations are causing an entire screen update (for example a small area in the top left corner and a small area in the bottom right corner).
You will find the implementation within Core::Root.
Do you have any issues with your GUI application?
Best regards,
Manfred