49.1.1 Merging Faces for Display

Here are all the ways to specify which face to use for display of text:

• With defaults. Each frame has a default face, which is used for all text that doesn’t somehow specify another face. The face named default applies to the text area, while the faces left-margin and right-margin apply to the left and right margin areas.
• With text properties. A character may have a face property; if so, it’s displayed with that face. (Text properties are actually implemented in terms of extents.) See Text Properties.
• With extents. An extent may have a face property, which applies to all the text covered by the extent; in addition, if the highlight property is set, the highlight property applies when the mouse moves over the extent or if the extent is explicitly highlighted. See Extents.
• With annotations. Annotations that are inserted into a buffer can specify their own face. (Annotations are actually implemented in terms of extents.) See Annotations.

If these various sources together specify more than one face for a particular character, SXEmacs merges the properties of the various faces specified. Extents, text properties, and annotations all use the same underlying representation (as extents). When multiple extents cover one character, an extent with higher priority overrides those with lower priority. See Extents. If no extent covers a particular character, the default face is used.

If a background pixmap is specified, it determines what will be displayed in the background of text characters. If the background pixmap is actually a pixmap, with its colors specified, those colors are used; if it is a bitmap, the face’s foreground and background colors are used to color it.