This new update 13 is another large one! It focuses on style/skins and user interface (UI). I tried to implement as many related suggestions as possible, so I hope it will meet your expectations ;)

Here are the main changes:

• Advanced skins -- You can now customize tree, water & lava colors, and add a global color teint.
• Interface update -- Many interface components were updated to fix user experience issues.
  • The toolbar can be displayed in 2 or 3 columns mode (3-columns is now the default, this can be changed in the Settings).
  • New Map Aspect panel: all these settings are now in a docked panel. You can scroll/zoom/move the map even if this panel is open.
  • App Settings are now stored in a panel ; you can access it from the top-right corner of the window.
  • Windows such as Text editor or Mob editor can no longer leave the screen.
• New assets -- This update includes new Trees, new Dirt, and a new Heavy Dirt object! 
• Assets overlapping -- Many elements (dirt, trees, furnitures...) can now be painted over the walls
• Special waters -- Available water pools are now "Clear water", "Special water 1" and "Special water 2" (instead of water/lava). They can all be customised from the Map Aspect panel. So you may now add acid water pools, dark water and lava in the same map :)
• "Light/Dark" grayscale skins -- They replace the old "Black & White". They can be combined with global teints for more effects!
• New "Dark" skin -- This skin features black walls and steel colors.
• New resize/panning -- Many optimizations when using Resizing and Panning options. They should now be much faster for large maps.
• Added new fog colors
• Colorless lights in Grayscale mode are now really transparent
• Texts can now have an optional drop shadow or an outline.
• Updated the default aspect of maps imported from external apps.
• Moved the optional "New Update" button to the tool bar
• Bug fixes and some internal house-keeping
• Updated all example maps