Show an app on Slingshot

Question

I was instructed that by adding the line OnlyShowin=Pantheon in the .desktop file of an app, would make it show on Slingshot menus. I did that with gufw (the firewall app), but it didn't happen. Please advise on what I'm missing. The .desktop file (located in /usr/share/applications) is as follows:

[Desktop Entry] 
Version=1.0 
Name=Firewall Configuration 
Comment=An easy way to configure your firewall
Categories=GNOME;GTK;Settings;Security;X-GNOME-Settings-Panel;X-GNOME-SystemSett‌​ings;X-Unity-Settings-Panel;X-XFCE-SettingsDialog;X-XFCE-SystemSettings;System 
Exec=gufw 
Icon=gufw 
Terminal=false 
Type=Application 
X-GNOME-Settings-Panel=gufw 
X-Unity-Settings-Panel=gufw 
X-Ubuntu-Gettext-Domain=gufw

Answer 1

Remove OnlyShowin=Pantheon from the .desktop file. I didn't have to add OnlyShowin=Pantheon to get my .desktop file to show in Slingshot.

Answer 2

If you place the .desktop file in ~/.local/share/applications instead of /usr/share/applications, does that fix the problem?

From the Human Interface Guidelines:

Users may create their own launchers by putting .desktop files in ~/.local/share/applications.

Answer 3

If what you are trying to achieve is to show an application or program in the Slingshot menu, I have done it by following the instructions located here.

Which in short are:

sudo apt-get install --no-install-recommends alacarte

Then

sudo scratch-text-editor /usr/share/alacarte/Alacarte/MenuEditor.py

There you have to replace the string applications.menu with pantheon-applications.menu (all occurrences).

Finally, from the terminal: sudo alacarte

And there, you're done. You can now add shortcuts to the Slingshot menu and personalize categories.