In this screenshot, you can see icons at the right. These are are not special dock icons made of .png files - they are ordinary icons that sit on your desktop. But Ive made them in a way that the icon itself is missing, and the text itself is the only thing clickable and visible.
How to create them:
1 - create a transparent .png file
2 - create a desktop file of whatever function (shortcut to FireFox, for example)
3 - right click on icon, select stretch icon, make it as small as possible
4 - change the icon of the file and instead select the transparent .png