Left drag - rotate the camera (look around) Right drag - rotate around the current object (orbit) Middle drag - change the FOV Left + Right drag - change the distance to the current object (zoom; works in the Map mode)
Left click - select an object Right click - select an object and call context menu Middle click - return previous/default FOV
Wheel - change speed
The context menu is slightly different for different types of objects. If you select the "Moons" or "Planets" it opens the Solar system browser at the selected object's level (i.e. right click on the planet -> Moon -> a browser with moons of this planet has opened).
Also I have replace an ugly purple loading progress bar with annoying messages with a small rotating icon near the FPS counter:
These loading messages are still shown in the Debug mode. This info was really needed only for debug purposes, there are many videos on youtube where people forgot to disable the HUD or change it simply with Ctrl-~. I think these rotating icon will look much better and not so annoying as the huge blinking progress bar.