I upgraded to Ubuntu 14.10 today, and in its version of gedit (3.10.4), the spell-checking plugin highlights misspelled words in light grey. Is there a way to change it back to red? I poked around the Color Scheme Editor and couldn't find a corresponding style.
Ubuntu – How to change the color of gedit’s spell checking underline
colorsgeditspell-checking
Related Solutions
As wojox said, you can change Gedit's theme.
The gtksourceview page on the Gnome website has more information about gedit themes. (Gtksourceview is the name of the software component that displays text in gedit.)
Modifying Existing Themes
To modify the built-in themes, copy them from /usr/share/gtksourceview-2.0/styles/ to ~/.local/share/gtksourceview-2.0/styles/ and edit the text files.
Finding New Themes
You can find several themes in this git repository. It looks like you can install them with:
sudo apt-get install git-core
git clone https://github.com/mig/gedit-themes.git ~/.gnome2/gedit/styles
(This will allow you to run cd ~/.gnome2/gedit/styles ; git pull to get updates to these themes.)
Building Your Own
You can also try this online theme generator. I found that on this article about creating gtksourceview themes.
Open the dictionairy where your words are saved and remove them. You can find these by opening home folder, hit control-h (shows hidden files) and navigate ~/.config/enchant
I myself have 1 dic file in there and you can open it in gedit.
Best Answer
This is not really an answer to the problem, but a quick trick:
change the set of colors used by gedit in the preferences. In some sets the light gray is clearly visible.