There wont be clickable minimize and maximize buttons on every window by default. Be it Firefox or Terminal window, the only option is to close the window. Enable minimize button in Fedora 29 , Ubuntu, Cent OS systems using the simple trick mentioned below. Enable minimize maximize button linux.
Enable minimize maximize button linux
First you need to install “gnome-tweak-tool” package using the command below
[[email protected] ~]$ sudo yum -y install gnome-tweak-tool 
After installng the package, open “Gnome tweak tool” 
Open the gnome tweak tool and enable minimize and maximize titlebar buttons. 
thanks brother