If you use an application very often you'll probably want faster access to it. In GNOME, you can add a single application or an entire menu to the the panel.

If you'd like to start an application directly from a launch button on your panel, try the following:

From the Main Menu, drag & drop a menu entry on an empty area of the panel. This should create a brand-new icon in your panel, similar to the one in the bottom example.