When you start playing SP for the first time, building tips pop up in the designer. I don't know all of them, but some include:

• Pressing control key when dragging doesn't select parts (useful for moving the viewport).
• Right click and drag clones a part.
• Left click shows more part details.
• The gear icon opens part properties.

If anyone could elaborate on these designer pop-up tips and/or add some more, that would be much appreciated.