The bug has been opened on https://bugs.launchpad.net/bugs/113246

"Binary package hint: gedit

Open a text file with very long lines. I'm not sure what the limit is but my test case is a 30k sql file with a single insert on 1 line. I'll attach a screenshot if I can but essentially the line wraps on itself and becomes illegible.

http://librarian.launchpad.net/7580368/Screenshot-gedit.png
Screenshot-gedit.png

Here's a screenshot demonstrating the bug.
...
This is with gedit 2.18.1 in Feisty. I'm not sure what you mean about attaching an example. I attached a screenshot. Do you mean a sample text file? I'm playing with creating a sample now and have discovered a few things.

1. Around 4100+ characters (on a single line) the text becomes invisible for a while. It does not wrap but simply is cut off in the display. The cursor still moves through it though so it must be there.

2. Around 40K characters switching syntax highlighting is a huge mistake (the entire desktop froze so long I thought it was hung).

http://librarian.launchpad.net/7687360/sample.txt
Sample text file

This sample does not show the wrapping problem shown in my screen capture but does demonstrate 2 other symptoms.

1. Sample line 1 is 4225 characters long. Pressing the 'end' key on that line will
show no text at the cursor but moving the cursor back to 4100 something will
cause the text to suddenly appear.

2. Sample line 2 is 29569 characters long. Moving the horizontal scrollbar will
show the text of this document truncated at a certain point and repeated with
large gaps of nothing inbetween.

I have an SQL sample with only 9K characters on a line which is showing the wrapping symptom but it is in french and contains a lot of accented characters so I cannot be certain if that is a factor. Syntax highlighting does not seem to be the main cause because I see the problem with no highlighting and with any other syntax though it does suffer under these conditions.

http://librarian.launchpad.net/7733200/fckeditorcode_gecko.js
fckeditorcode_gecko.js

This javascript file exhibits the "wrapping" problem."