How panes are arranged
The Diff Merge display varies, depending on whether the tool is used within the context of a merge or is used only to compare files, directories, or versions.
If you are merging
If Diff Merge is used within the context of a merge, it displays two or more contributor panes and one merge results pane. (On Windows systems, if you are merging HTML contributors, Diff Merge displays an HTML browser pane above or below the contributor panes.)
Contributor panes show the file or directory contents of a given contributor to the merge. These numbered panes are arranged either horizontally or vertically. The base contributor (labeled Base in the title bar) is the first contributor, the to-version (labeled To-version in the title bar) is the last contributor, and all other contributors are displayed between them.
The merge results pane is displayed above or below the contributor panes and is not numbered. If you resolve differences between contributors, the changes are displayed in this pane.
On Windows systems, the HTML browser pane (labeled Previewing in the title bar) renders and displays the HTML content of the currently selected contributor. The number of the contributor being displayed is displayed in the title bar.
If you are comparing and not merging
When you use Diff Merge to compare elements but are not merging, only the contributor panes are displayed. There is no merge result pane. (On Windows systems, if you are comparing HTML contributors, Diff Merge displays an HTML browser pane above or below the contributor panes.)