Hi
In a MdiWindowListTool, we can add a "close all windows" by setting the DisplayCloseWindowsCommand to True.
Is there a way to add a "close all but this" to this same object?
No, this would have to be added manually as a separate ButtonTool with custom logic to close all mdi children expect the active mdi child. You can also submit a feature request for the MdiWindowListTool to do this: http://devcenter.infragistics.com/Protected/RequestFeature.aspx.
Do you have an example of adding a button to the MdiWindowListTool?
You cannot add a button to the MdiWindowListTool. You would need to add a ButtonTool directly above or below the MdiWindowListTool.