According to Bugreports
The Font and Background Color "Automatic" Depend on Theme settings which I believe to be confusing and wrong.
This seems to apply primarily to Ubuntu/other Linux variants.
I reproduced it in 12.04
A Fix seems to be to set the Colors in Extras->Settings->LibreOffice->Appearance "Font Color" and "Background Color" to non automatic - black and white.
This would be a premanent solution if "automatic" is actually ment to behave that way.
isnt this a dupe/already fixed with fdo#353665/lp#628105?
please check with LibreOffice 4.0.x
*** This bug has been marked as a duplicate of bug 35365 ***