IDE Window: Editor Options Display Gutter
The Lazarus IDE has an optional file overview feature called an "overview gutter". This gutter is the thin vertical bar adjacent to the source editor's vertical scrollbar. You can show or hide the overview gutter via the "Show overview gutter" checkbox found on the IDE Options dialog's Editor / Display page (the fourth checkbox in the "Margin and gutter" groupbox).
When editing Pascal files the overview gutter shows a compressed summary of line and unit information:
- modified lines: a yellow square shows recent unsaved modifications; green squares show saved modified lines
- left-gutter marks: breakpoints (red), bookmarks (blue), compilation errors (orange)
- interface/implementation/finalization sections are shown in various shades of grey
- the location of the current editor page relative to the rest of the edited file is shown in another shade of grey
If you click on a rectangular coloured mark, you jump to the relevant location in the text. Clicking anywhere on the overview gutter jumps you to the position in the file that gutter point represents, i. e. the top of the gutter represents the start of the file and the bottom of the gutter represents the end of the file.