The Shape Order filter lists all shapes (paths and components) of a glyph across all layers.
Paths are shown in navy blue; components in brown.
Each column lists the shapes of a master/
Columns are separated by a gray gutter if there are multiple independent interpolations for the glyph. That might be the case when using intermediate layers or when employing a complex master setup (for example, when condensed masters interpolate independently of extended masters).
The Shape Order filter is useful when Path → Correct Path Directions for all Masters (Cmd-Opt-Shift-R) does not yield the desired master compatibility.