Harvest v14 introduces a new feature--when do cross project merger, you would need to choose one file and then click on <- arrow to merge it. This is not an issue if the project has a couple of files . However, when the project has a couple of hundreds of files, this will take long time. This tech explains what you can do to disable the preview so all files will merge automatically.
Release : 14.0
Component : Harvest
From Harvest workbench, Tools -> Preferences and then check the checkbox for
"Launch CrossProjectMerge window without preview"
And from this moment one, no preview will be presented and the merge will be done for all files automatically.