Changes detected infobar should be a dialog
This is not quite an appropriate use of an infobar as it's doing more than communicate information about the state of the file and is asking a person to make a decision, i.e. whether to reload or not, and therefore should probably be a message dialog.
Obviously we don't want a dozen dialogs popping up when a dozen files are changed externally so I was thinking that the dialog would only appear when you revisited the file in builder.