VS 2003+Auto-Load File Changes in Visual Studio
When files are shared between Visual Studio projects, it is common for those files to be changed by other users or in other editing software. Visual Studio can be configured to detect these changes and reload source code automatically.
Detecting Changes
If you work with files that are shared between projects, or that are accessible by more than one developer, it is possible that a file can be edited outside of Visual Studio. When using the default configuration, Visual Studio detects that files have been changed and displays a warning. The message box includes the option to load the changed file or to use the version held in memory. This can increase the risk that changes made outside of Visual Studio could be overwritten accidentally.
You can reconfigure Visual Studio to ignore changes in other files completely, or to automatically load new versions without displaying the warning message. This is achieved by choosing "Options" from the Tools menu to display the Options dialog box. Select "Documents" from the "Environment" section of the tree structure to the left of the dialog box. Two checkboxes can now be used to alter the change detection action. By unchecking "Detect when file is changed outside the environment", unexpected changes will be ignored. If this option is enabled, ticking the "Auto-load changes, if saved" checkbox causes changes to be loaded without showing a warning.
NB: The wording of the checkboxes varies depending upon the version of Visual Studio in use.
30 March 2010