Minecraft wiki entry for Development_versions, associated text: When using the new touch controls on mobile devices, the size of the thumbstick can now be adjusted with the Button Size slider in the settings screen
Fixed an issue in Pocket UI where items could be dropped unintentionally in blocks with custom UIs, and resized those screens to allow for dropping items on the sides instead
Improved contrast on multiple UI elements
Enabled the Behavior Packs tab in the new Create New World screen