Merge enables you to edit files by typing text directly into them. Click within one of the files to make it active and then use the keyboard to make any required changes.
Use Cmd+C to copy text from one file to the clipboard and Cmd+V to paste it into the other file. You can also select blocks of text and drag/drop them to and from any file panel in Merge and to many other applications. Hold down the Cmd key when you drop the selected text to move it to the drop location, or drop without pressing any keys to copy it.
As you make changes to the files, Merge performs background comparisons to ensure that the displayed comparison results are always up-to-date.
Modified indicator
When a file has been modified, an indicator icon Modified 
appears next to the edit field at the top of the window.
Edit markers and bookmarks
As you edit files, Merge will automatically create edit markers 
to indicate lines that you have modified. To navigate between edits click the Previous Edit 
and Next Edit 
toolbar buttons. You can also select the Edit▸Markers▸Previous Edit and Edit▸Markers▸Next Edit menu items, or press Shift+F3 and F3.
To toggle a bookmark for the current line on or off, click the Bookmarks 
toolbar button and select Toggle Bookmark. You can also select the Edit▸Bookmarks▸Toggle Bookmark menu item, or press Cmd+F2.
To navigate bookmarks, click the Bookmarks toolbar button and select Next Bookmark or Previous Bookmark. You can also select the Edit▸Bookmarks▸Next Bookmark or Edit▸Bookmarks▸Previous Bookmark menu items, or press F2 or Shift+F2.
Comments can be added to both edit markers and bookmarks, making it easy to note important information or to record a question. To edit a marker or bookmark’s comment, right-click the bookmark and choose the Edit Comment… menu item. Comments are shown as tooltips when you hover the mouse pointer over an edit marker or bookmark.
Bookmarks and comments are included when you save a comparison for archival or team collaboration. Bookmark comments are also shown in HTML comparison reports. They are therefore a useful tool for asking questions or making notes in a comparison that will later be emailed to other team members for review.
Undoing changes
To undo or redo changes you have made while editing click the Undo 
or Redo 
toolbar buttons. You can also select the Edit▸Undo and Edit▸Redo menu items, or press Cmd+Z or Shift+Cmd+Z.
Read-only files
When a file is read-only on disk, an indicator icon Read-only 
appears next to the entry field at the top of the window.
By default, Merge does not allow you to make changes to files that are marked read-only on disk. Merge will ask whether you wish to override this should you attempt to edit a read-only file.
Merging files
In addition to the editing features described above, several tools are provided to make it easier to merge changes from one file into another. Please see the Merging Files topic for more information.