The font, font size, foreground color and background color of Tooltips in Ubuntu can be changed. This can be important since Tooltips are used by applications in Eclipse.
- To change the font and the font size: Open GNOME Tweak Tool, go to Fonts section and set the font and font size for the Interface element.
To change the foreground and background colors: Open GNOME Color Chooser, go to Specific -> Tooltips and set the colors you want.
Restart your application to see the effect of these changes.
Tried with: GNOME Tweak Tool 3.10.1-2, GNOME Color Chooser 0.2.5 and Ubuntu 14.04