Graph: pan with left or right, open with the other

Client/Core.py

@@ -168,9 +168,10 @@ class AppConfig:
     # in place (like Obsidian's live preview). Only affects Markdown.
     MarkdownEditing: str = "Live"
     # Graph view: directories as dots too (off: only files and the references
-    # between them), and the mouse button that pans ("Left", "Middle", "Right").
+    # between them), and the mouse button that pans ("Left" or "Right"; the
+    # other one opens a dot).
     GraphShowDirectories: bool = True
-    GraphPanButton: str = "Middle"
+    GraphPanButton: str = "Right"
     # Double-click on a file: True opens it in SaraView's own viewer, False
     # hands it to the system's default program. The menu always offers the other.
     OpenFilesInApp: bool = True