

holding control lets you select objects from inside groups, without ungrouping them first. Holding Ctrl it says "Click to select in groups drag to move hor/ver" - i.e.Shift+drag starts a rubberband selection without selecting or moving the object you start dragging on (vital for very complex drawings with overlapping objects).

shift-click toggles the selection on/off of individual items. Holding Shift it says "Click to toggle select drag for rubberband selection" - i.e.It doesn't mention the Ctrl and Alt options, though.

This tells you that you can select objects with a click (which only selects one), shift-click (which lets you multi-select) or dragging around objects ("rubberband" selection).
