Steam achievements for completing all levels in a category for untimed content have now been added to the game. If you previously completed all levels in a category, you did not receive the achievement, but the status is still saved in the game. Reopening the game should trigger the achievement.
The keyboard shortcut for in-game hints has been changed from SHIFT+"H" to "?" key. This was changed to avoid users accidentally triggering hints when typing letters on the keyboard while holding down the Shift key.