50.3.4 Frame Glyphs

There are also a number of special objects whose appearance is specified by a glyph. Most of these a global objects that you update with set-glyph-image, such as mouse pointers. Frame icons, toolbar button icons, and the modeline are the main non-text objects which accept glyphs as elements.

modeline

A glyph may be displayed in the modeline by inserting the glyph as one of the elements of the modeline format. (Unfortunately you can’t currently put a begin glyph or end glyph on one of the modeline extents—they’re ignored.)

toolbar

To insert a glyph into a toolbar, specify it as the icon part of a toolbar button, which in turn must be part of a toolbar instantiator (typically set on the specifier default-toolbar). See default-toolbar for more information. (As a convenience, you may use a symbol in place of the glyph list in the toolbar button instantiator; the symbol is evalled to get the glyph list. This facilitates both creating the toolbar instantiator and modifying individual glyphs in a toolbar later on. For example, you can change the way that the Mail toolbar button looks by modifying the value of the variable toolbar-mail-icon (in general, toolbar-*-icon) and then calling (set-specifier-dirty-flag default-toolbar). (#### Unfortunately this doesn’t quite work the way it should; the change will appear in new frames, but not existing ones, because once an image has been displayed the pixmap replaces the symbol for those domains.)

gutter

To insert a glyph into a gutter, use set-extent-begin-glyph or set-extent-end-glyph to set a glyph to be displayed at the corresponding edge of extent in a string, similar to the way you insert glyphs in a buffer. Then insert the string into the gutter Specifying a Gutter. Glyphs that are frequently used in this way are tab control and progress bar glyphs.