https://bugs.gentoo.org/690014
https://sourceforge.net/p/gnuplot/mailman/message/34342174/

--- gnuplot-5.2.6-orig/configure.ac
+++ gnuplot-5.2.6/configure.ac
@@ -1224,6 +1224,7 @@
 if test "${enable_qt_ok}" = yes \
   || test "${enable_wxwidgets_ok}" = yes \
   || test "$GGI_SUPPORT" = yes \
+  || test "$with_caca" = yes \
   || test "$no_x" != yes; then
     enable_mouse=yes;
 fi
