Fix: avoid tagging file as modified when clicking in node editor

source/blender/blenkernel/BKE_node.hh

@@ -642,7 +642,11 @@ bool nodeIsParentAndChild(const bNode *parent, const bNode *child);
 
 int nodeCountSocketLinks(const bNodeTree *ntree, const bNodeSocket *sock);
 
-void nodeSetSelected(bNode *node, bool select);
+/**
+ * Selects or deselects the node. If the node is deselected, all its sockets are deselected too.
+ * \return True if any selection was changed.
+ */
+bool nodeSetSelected(bNode *node, bool select);
 /**
  * Two active flags, ID nodes have special flag for buttons display.
  */

source/blender/blenkernel/intern/node.cc

@@ -3839,20 +3839,26 @@ bNode *nodeGetActive(bNodeTree *ntree)
   return nullptr;
 }
 
-void nodeSetSelected(bNode *node, const bool select)
+bool nodeSetSelected(bNode *node, const bool select)
 {
-  if (select) {
-    node->flag |= NODE_SELECT;
-    return;
+  bool changed = false;
+  if (select != ((node->flag & NODE_SELECT) != 0)) {
+    changed = true;
+    SET_FLAG_FROM_TEST(node->flag, select, NODE_SELECT);
   }
-  node->flag &= ~NODE_SELECT;
-  /* deselect sockets too */
+  if (select) {
+    return changed;
+  }
+  /* Deselect sockets too. */
   LISTBASE_FOREACH (bNodeSocket *, sock, &node->inputs) {
+    changed |= (sock->flag & NODE_SELECT) != 0;
     sock->flag &= ~NODE_SELECT;
   }
   LISTBASE_FOREACH (bNodeSocket *, sock, &node->outputs) {
+    changed |= (sock->flag & NODE_SELECT) != 0;
     sock->flag &= ~NODE_SELECT;
   }
+  return changed;
 }
 
 void nodeClearActive(bNodeTree *ntree)

source/blender/editors/space_node/node_intern.hh

@@ -203,7 +203,7 @@ void node_keymap(wmKeyConfig *keyconf);
 rctf node_frame_rect_inside(const SpaceNode &snode, const bNode &node);
 bool node_or_socket_isect_event(const bContext &C, const wmEvent &event);
 
-void node_deselect_all(bNodeTree &node_tree);
+bool node_deselect_all(bNodeTree &node_tree);
 void node_socket_select(bNode *node, bNodeSocket &sock);
 void node_socket_deselect(bNode *node, bNodeSocket &sock, bool deselect_node);
 void node_deselect_all_input_sockets(bNodeTree &node_tree, bool deselect_nodes);

source/blender/editors/space_node/node_select.cc

@@ -245,11 +245,13 @@ static void node_socket_toggle(bNode *node, bNodeSocket &sock, bool deselect_nod
   }
 }
 
-void node_deselect_all(bNodeTree &node_tree)
+bool node_deselect_all(bNodeTree &node_tree)
 {
+  bool changed = false;
   for (bNode *node : node_tree.all_nodes()) {
-    nodeSetSelected(node, false);
+    changed |= nodeSetSelected(node, false);
   }
+  return changed;
 }
 
 void node_deselect_all_input_sockets(bNodeTree &node_tree, const bool deselect_nodes)
@@ -631,8 +633,7 @@ static bool node_mouse_select(bContext *C,
       }
       else if (found || params->deselect_all) {
         /* Deselect everything. */
-        node_deselect_all(node_tree);
-        changed = true;
+        changed = node_deselect_all(node_tree);
       }
     }