Sorry about this; the bug is now fixed and as soon as we roll out 1.50, later this week, this problem will go away permanently. In the meantime, there are two workarounds. If you want to play in fullscreen, hide your Dock before starting the game (Control-click or right-click on the Dock and choose “Turn Hiding On” from the menu that pops up).
Alternatively, you can leave your Dock the way it is and just play in windowed mode at essentially the same resolution; click Options on the main menu (by clicking an inch above it!), uncheck the full screen box, and choose the highest resolution listed in the box to the left. Quit and restart, and you’ll be playing almost fullscreen – just with a window title bar at the top – and clicking should behave properly.