ggtern creates many new theme elements and inheritances, the following is an outline:
** NB: tern.panel.background, whilst the ternary area is 'triangular' per-se, element_rect has been used,
as it actually holds NO information regarding the geometry (width, height), only fill, color,
size and linetype border (ie the style of how it will be rendered).
Nicholas Hamilton
Theme elements can inherit properties from other theme elements.
For example, axis.title.x inherits from axis.title,
which in turn inherits from text. All text elements inherit
directly or indirectly from text; all lines inherit from
line, and all rectangular objects inherit from rect.
Modifying the newly created items requires the same procedures as introduced in the ggplot2 theme documentation.
Some convenience functions have been also newly created, proceed to theme_convenience_functions for additional information.