menu entry plot2d can't produce any plots

[fabtagon]

The menu entry plot2d seems unfit to invoke actual plots.

  (%i1) f(x):=x;
  (%o1) f(x):=x

Put cursor on first line, go plot > plot 2d, expression is pre-set to f(x):=x, just click ok

  (%i2) plot2d([f(x):=x], [x,-5,5])$
  plot2d: expression evaluates to non-numeric value everywhere in plotting range.
  plot2d: nothing to plot.

(Setting expression to 'h(x):=x' in dialog gives same problem)
What works though is specifying the function by name as first argument to plot2d (notice it has been given as "[f(x):=x]) when invoked from the menu:

  (%i3) plot2d(f(x),[x,-5,5]);
  (%o3) ["/tmp/maxout11321.gnuplot_pipes"]
  [graphics comes up]

Expectation would of course be that whatever the menu entry does, results in a plot and not in an error.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: wxmaxima 18.02.0-2
ProcVersionSignature: Ubuntu 4.15.0-34.37-generic 4.15.18
Uname: Linux 4.15.0-34-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.2
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Sat Sep 29 00:48:02 2018
InstallationDate: Installed on 2015-04-27 (1250 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
SourcePackage: wxmaxima
UpgradeStatus: Upgraded to bionic on 2018-08-18 (41 days ago)