You can opt in to the experimental branch by right clicking on "Species", selecting "Properties" and going to the "Betas" tab.
Changelog:
* Dropdown menu's now display on top of all other controls except ToolTips
* Dropdown menu's now hold focus when you click them, so that they don't interact with controls behind them
* Fixed issue with terrain-height brushes sometimes raising/lowering/flattening terrain to the left or right of the brush location, instead of under the brush.
* Water height is now set correctly when adjusted in Map Editor and Quickstart
* Fixed some incorrectly positioned UI controls
* Improved menu performance when eroding/generating sediment map