You can import objects from previously saved simulations using File>>Import menu
You can keep tool selected by Double clicking the tool in toolbar
You can use keys to switch between tools, refer help for more.
You can resize widgets by dragging at right Corner
You can use Page Up/Page Down for continuous zoom
You can perform multi-selection by holding Ctrl during selection
You can copy and paste objects in simulation using Ctrl X and Ctrl V
You can create objects from Text using Text-Tool in miscellaneous toolbar
you can slice Objects/remove joints using slice tool in miscellaneous toolbar
You can flip selected objects(s) by pressing flip in pop-up menu 
You can create graph for objects by selecting graph tool and clicking on body
FBD for multi-selection treats selected objects as system 
You can pause and resume simulation by pressing SPACE key
Pressing key 'Q' simulates scene in steps
You can save and restore state of simulation using menu File>>SnapShot
You can fit scene to screen by selecting option from pop-up menu on canvas
You can write your own script at world events like start, update and stop
You can edit body to set collision response of body as killer, sticky or immortal
You can edit world to add/remove electrostatic, magnetic and buoyancy fields
You can change Z-order of objects from right click pop-up menu
You can observe simulation in different frame by attaching camera on body