The Mono Font View command on the View menu toggles the Mono Font View mode on and off. When this mode is on, all syntax formatting is suppressed, except for color changes, and a mono-spaced font is used.
Use Mono Font View to quickly see how text columns lines up. You can edit the Mono Font View font in Style Properties
All text is displayed using the "Mono Font View" style, which can be edited with the Style Properties dialog box. The "Mono Font View" style is preset to use a mono-spaced font. See: Style Properties.
The Syntax Formatting features of Source Insight are powerful, and allow you to use a variable pitch font if you want, but sometimes you need to see how text will line up in another editor or in a simple display mode when only a single font is used. Mono Font mode is useful for quickly switching your display to a basic mono-spaced font display. This is particularly useful if you are using spaces instead of tab characters to line columns up.
When Mono Font mode is active, it overrides the settings of the Preferences: Syntax Formatting and Syntax Decorations dialog boxes.