Edit Mode can be enabled and disabled from the Edit menu. A tick will appear next to the Edit Mode menu item when enabled and 'Edit Mode' will be shown at the top of the window.
It can also be enabled by selecting the option in the Positioning toolbar at the top of the canvas.
When Edit Mode is enabled, the figure joints can be repositioned by dragging the handle without effecting the position of any other joint. The length of the segments connected to the moved joint will therefore change.
When Edit Mode is disabled, the figure can be moved as a normal figure - this includes the use of the Ctrl key to change the length of a segment and the Alt key to scale or rotate the entire figure.
Holding the R key while dragging a handle is equivalent to dragging a handle while in Edit Mode but can be used at any time and even when positioning figures in the main animation window.