The GUI needs GTK 1.2.x or GTK 2.0 (it isn't fully GTK, but the panels are),
so GTK
(and the devel stuff, usually
called gtk-dev
) has to be installed.
You can build it by specifying --enable-gui during
./configure. Then, to turn on GUI mode, you have to
execute the gmplayer binary.
In order to use the GUI in a comfortable way and as intended, you are
strongly advised to install a skin. See Skins at the download page.
A skin should be extracted to the usual system-wide directory $PREFIX/share/mplayer/skins or to the user
specific directory $HOME/.mplayer/skins
and resides as a subdirectory there.
MPlayer by default first looks in the user specific
directory, then the system-wide directory for a subdirectory named
default (which
simply can be a link to your favourite skin) to load the skin, but
you can use the -skin myskin
option, or the skin=myskin
or gui_skin=myskin
config file directives, or the skin browser to use
a different skin from the skins
directories.