Version 4.18.12

• the menu has been replaced with a full-screen activity selection screen
  • this allows displaying all activity icons without scrolling
  • more space for activities since the menu does not take up any screen space while in activity mode
  • the icons on new menu screen now display progress for each challenge activity
  • the category and activity icons have been redesigned and scaled up
  • categories rearranged into sub-groups to display fewer choices at a time.
• theme editing screen added to customize UI and menu colours
• a number of new activities added - covering elapsed time as well as negative numbers
• new activities on equivalent fractions as well as addition, subtraction, multiplication and division of fractions
• a lot of cosmetic fixes across the application