The FontManager in Tycho a top-level window within which you can select a font. When you select a font, the alphabet will be displayed in that font. When you have invoked the font manager from within an editor, the clicking OK or typing return will set the selected font in the editor.
Rather than exposing to the user the arcane font specification that is used by the X window system, the font manager has five pull-down menus that can be used to select fonts by family, size, weight, and style. Since some of the best X window fonts do not conform to this partitioning, a separate menu is provided for selecting miscellaneous fonts by name. For example, the 9x15 and 10x20 fonts are particularly nice screen fonts.