white clue has to be a corner, but don't yet know which way the corner
turns, you might mark the one way it \e{can't} go with a cross.)
+Alternatively, use the cursor keys to move the cursor. Use the Enter
+key to begin and end keyboard `drag' operations. Use the Space key to
+cancel the drag. Use Ctrl-arrowkey and Shift-arrowkey to simulate a
+left or right click, respectively, on the edge in the given direction
+relative to the cursor, i.e. to draw a segment or a cross.
+
(All the actions described in \k{common-actions} are also available.)
\H{pearl-parameters} \I{parameters, for Pearl}Pearl parameters