Text and fonts
Gimp text is based on the way X manages fonts. In this chapter, we'll try to shed some light on the matter.
Note! You might be fooled to think that you got "a real border". When you fill letters in a text layer with a different color than before, it might actually look like a sort of border around your letters. This has nothing to do with the Border option in the Text tool dialog. Instead, it is due to a low fill-threshold in the Bucket fill options dialog. With a low threshold, the Bucket tool won't fill semi-transparent pixels, and they will stand out against the fill because they have kept their original color. With a higher threshold everything will be filled with the same color.
The Gimp User Manual
Last modified: 19 May 1998