The following works on Open­So­laris with GNOME 2.28.2

$ gconftool-2 -t string -s \
"/apps/metacity/general/button_layout" \
"close,minimize,maximize:menu"

1. Install SUNWmlib package.
2. Save flash_player_10_solaris.x86.tar.gz from http://get.adobe.com/flash­play­er/ to ~/Downloads.

3. Open a terminal and execute the following:

   cd ~/Downloads
   tar xjvf flash_player_10_solaris_x86.tar.bz2
   pfexec cp ~/Downloads/flash_player_10_solaris_r42_34_x86/libflashplayer.so /usr/lib/firefox/plugins

4. Restart Firefox