+ {@# No search query
+
+@# We have the following possible cases:
+@# choose.which dir re result
+@# choose "" - Ask for top level
+@# choose "" present Ask for top level with re applied
+@# choose present - Ask for dir
+@# choose present re Ask for dir with re applied
+@# choosealpha "" - Nothing
+@# choosealpha "" present Ask for top level with re applied
+@# choosealpha present - Ask for dir
+@# choosealpha present re Ask for dir with re applied
+@#
+@# So in fact the only oddity is choosealpha + no dir + no re.
+@#
+@# NB we don't really bother distinguishing between re being empty or absent,
+@# and the server deliberately cooperates in this.