c_gtk_source_gutter_lines_get_line_yrange

Undocumented in source but is binding to C. You might be able to learn more by searching the web for its name.
extern (C) __gshared
void function(GtkSourceGutterLines* lines, uint line, GtkSourceGutterRendererAlignmentMode mode, int* y, int* height) c_gtk_source_gutter_lines_get_line_yrange;

Meta