2.5D Free Grease Pencil
The term 2.5D Free Grease Pencil, or Free GP to make it short, has been introduced to StoryLiner to designate grease pencil objects of the scene that are contributing to the story and on which you want to draw on. They can be involved in the action, such as placeholders for 3D characters, or just represent props in the set.
Free GPs have nothing special and can be any grease pencil objects. Usually they tend to be flat though, in order to easily draw on them.
The 2.5D Free Grease Pencil panel
By default the panel is only available when the current layout is set to Hybrid. It is possible to make this panel visible also in other layouts, either from the add-on Preferences, that will become the default configuration for every new scene, or from the Feature Toggles panel, it will then only affect the current scene.
The controls and operators held by the panel, as well as its general UI organization, are very similar to those from the Storyboard Shot properties panel, this in order to provide a similar user experience.