Unetbootin has no GUI on Ubuntu GNOME

This is a known issue.

As a workaround that does not require reinstalling unetbootin, you can run this command:

sudo QT_X11_NO_MITSHM=1 unetbootin

What the above command does is disable shared memory access for running this Qt based application, allowing it to work properly on GNOME.

The PPA source for unetbootin in the accepted answer includes the prefix to disable shared memory access in the default run command so that launching it from the GUI shortcut just works without any hassle: https://launchpad.net/~gezakovacs/+archive/ubuntu/ppa

Source of answer: https://github.com/unetbootin/unetbootin/issues/67

First uninstall your current version of unetbootin, then use official unetbootin page to install using ppa instead of deb files. If fails then try opening it from launcher instead of terminal.

I changed the Exec property in unetbootin.desktop:

Exec=/usr/bin/xdg-su -c /usr/bin/unetbootin

and created file /usr/bin/unetbootin with the bash script:

#!/bin/bash
QT_X11_NO_MITSHM=1 /usr/sbin/unetbootin

then made it exetutable:

sudo chmod +x /usr/sbin/unetbootin

and now when I run Unetbootin from my application overview it launches normally with GUI.