Ghosting

Ghosting (also know as onion skinning) displays the drawings on frames before and after the current frame. These drawings are semi-transparent to help distinguish them from the current frame.

The display of ghosted frames can be toggled through the main menu (BP2->Ghosting) and the number of frames displayed and color overrides can be changed in the settings dialog (BP2->Ghosting->Settings...).

From the Toolbox:

Toggles the display of frames prior to the current time. Right-click on this button to change the ghosting settings.
Toggles the display of frames after to the current time. Right-click on this button to change the ghosting settings.

Notes:

By default, ghosting is temporarily disabled during playback (for performance). This feature can be turned off through the Preferences (BP2->Preferences...).