Running some versions of Gnome have weird issues with when it shows the "standard" three buttons (Minimize/Maximize/Close) at the top of a window. Some have it, some do not.
A nice way around this is to just tell Gnome to ALWAYS show them. The following command will do that for you:
gsettings set org.gnome.desktop.wm.preferences button-layout ":minimize,maximize,close"