Using Maxima 5.30 in Windows, plotting commands will create two windows. One with the plot and a second window with a gnuplot interactive shell
Enter the following command in Maxima/Xmaxima:
gnuplot_view_args: "-persist ~s";
and after that all plotting commands should show only the plot window and not the gnuplot shell.
To avoid having to do that every time you start a new session, add that command to the file maxima-init.mac (if that file does not exist, create it) in your Maxima User Directory (to find out the name of that directory type maxima_userdir; in Maxima/Xmaxima).
Up to version 4.6.2, the behavior of gnuplot was different in Linux/Mac or Windows. In Linux:
gnuplot file -
executes the commands in file and enters the interactive gnuplot shell
gnuplot -persists file
executes the commands and exists the interactive shell, leaving the plot window open.
In Windows, the behavior of those two previous commands were the opposite of what happened in Linux. To deal with that inconsistency, Maxima has been using "gnuplot -persist file" in Linux and "gnuplot file -" in Windows.
Gnuplot 4.6.3 has solved several bugs with the -persist option in Windows and the behavior of the two commands above has been made consistent with the Linux version.
If nobody has anything against it, I will modify plot.lisp in order to use "gnuplot -persist file" in all operating systems (well, it is actually "wgnuplot -persist file" in Windows) and write a note in INSTALL.win32 to tell peaople to use Gnuplot 4.6.3 or later.