To edit an existing XLL+ function, you should open the source file containing the function in DevStudio (or Visual Studio), and then use the XLL+ Function Wizard tool-button to start the Wizard. In Visual Studio .NET or 2005, you can also use the XLL+ Function Wizard menu item on the Tools menu).
Make any changes you require using the Wizard, and then click the OK button (or the File - Save & Exit menu option) to save your changes. You can use the Cancel button at any time to abandon your changes.
You can choose to edit a different function by selecting its name in the 'C' Name combo-box in the Function Wizard.
All changes to a function's source code are made in a single action within DevStudio. Thus you can use the Undo command in DevStudio to undo all the changes made by the Wizard in one step per function.