This type of GUI for running commands is basically known as "Run" interface. It's fairly simple idea.
In the Ubuntu's Unity environment Alt+F2 allows running specific commands using the default shell,
dash or Debian Amquist Shell. Of course, you have to remember that you are running commands "blindly", meaning without the
STDOUT output from command or
STDERR streams going. So unless you are running a GUI app, you won't know if your command failed or not.
There are tweaks for Gnome desktop environment to utilise the same keybinding as well, which if I am not mistaken , can be configured using from Gnome Tweak Tool
For blackbox desktop environment there exists
bbrun package, which also does very much the same functionality.
At the very bottom of things, one could build such tool by themselves, using any programming language available or desired. For instance, here's some examples
Shell script + zenity
exec $(zenity --entry --title "Enter command" --text "")
public class runSomething
public static void main(String  args) throws IOException
String cmd = JOptionPane.showInputDialog("Enter command:");