Priority Mode (check this for input to follow operator priority - quicker but can be confusing for some!)

: Create new expression (mouse must be in the red rectangle)
: Copy selection to clipboard
: Paste clipboard content into selection
: Cut selection and put it in clipboard
: selection using serializer
Backspace: delete selection or last input character
Tab: cycle through possible keyword completions
Enter: validate current completion
Arrows: move selection within expression: UP to parent expression, DOWN to subexpression, LEFT to previous sibling and RIGHT to next sibling