5.8 Highlighting erroneous lines

Highlighting is implemented with overlays and happens in the process sentinel, after calling the cleanup function. Two customizable faces are used: flymake-errline and flymake-warnline. Errors belonging outside the current buffer are considered to belong to line 1 of the current buffer.

If the option flymake-fringe-indicator-position is non-nil, errors and warnings are also highlighted in the left or right fringe, using the bitmaps specified by flymake-error-bitmap and flymake-warning-bitmap.