The editor has been designed with two gutters.
The left gutter summarises or depicts information about each individual line of text.
The right gutter gives a highly compressed overview of all lines in the file.
For Pascal files the background greys alternate to show the relative sizes and locations of major unit sections (interface, implementation, initialization, finalization).
In addition the "coloured rectangles" indicate the relative positions of specific left-gutter indications such as a breakpoint or bookmark or compilation error. The rectangles are coloured to correspond to the left-gutter markings (red for breakpoint, for example).