GuideLines in Visual Studio.

In Visual Studio, you can create a guideline in the editor window.
In this example, we set a guideline at position 80.

The guideline helps to keep the code width to 80 positions.

Setting a guideline requires a change in the registry. Use it at your own risk.
 

The following registry setting enables a guideline in Visual Studio 2003:

[HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\7.1\Text Editor]
"Guides"="RGB(255,128,128) 79"

The following registry setting enables a guideline in Visual Studio 2005:

[HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\8.0\Text Editor]
"Guides"="RGB(255,128,128) 79"

Microsoft has not documented this feature.
You also get a ruler in some other windows, for example in the Find results window.
 

You can download the reg-files below.

You should:

  1. save it to your harddisk by right-clicking the hyperlink below.
  2. check its contents.
  3. change the extension from .txt to .reg
  4. doubleclick on it.

(Doubleclicking a .reg file without checking its contents would be an extremely risky operation)

Download Guides 2003.txt

Download Guides 2005.txt