-void update_screen(int *current_line, int *temporary_line, int motion,
+// The value passed to this routine in current_focus_line is the index
+// of the line we should have highlited if there was no motion and if
+// it matched the matcher. So, the line actually highlighted is the
+// first one matching the matcher in that order: (1)
+// current_focus_line after motion, (2) the first with a greater
+// index, (3) the first with a lesser index.
+
+// The index of the line actually shown highlighted is written in
+// displayed_focus_line (it can be -1)
+
+// If there is a motion and a line is actually shown highlighted, its
+// value is written in current_focus_line.
+
+void update_screen(int *current_focus_line, int *displayed_focus_line,
+ int motion,