How to: Set Editor Options by File Type
You can specify the editor or designer in which documents of a certain type will open in the integrated development environment. For example, you can map a file extension to an editor that supports encoding.
Note
The dialog boxes and menu commands you see might differ from those described in Help depending on your active settings or edition. To change your settings, choose Import and Export Settings on the Tools menu. For more information, see Visual Studio Settings.
To specify which editor to open files in by extension
On the Tools menu, click Options.
Expand Text Editor, and then click File Extension.
In the Extension box, type the characters for the file name extension, without the preceding period.
In the Editor box, select the editor in which you want to open files that have the specified extension.
Click Add.
Click OK.
To specify which editor to open files in that do not have an extension
On the Tools menu, click Options.
Expand Text Editor, and then click File Extension.
Select Map extensionless files to and then select an editor or designer in the drop down list.
Click OK.