I also found this issue in 13w42b. The GUI font is white unless you hover over the item you are holding. Sometimes it also just decides to fix itself, I can't seem to distinguish a real pattern of behaviour, this was in singleplayer. I will add screenshots. I use a texture pack but I checked and the bug is still there with the standard MC texture pack.
James Ray
I also found this issue in 13w42b.
The GUI font is white unless you hover over the item you are holding.
Sometimes it also just decides to fix itself, I can't seem to distinguish a real pattern of behaviour, this was in singleplayer. I will add screenshots.
I use a texture pack but I checked and the bug is still there with the standard MC texture pack.