proper modelica text model editing

BEdit/src/bedit/gui/simulation_window.py

@@ -691,7 +691,27 @@ def _safe_file_stem(model_name: str) -> str:
 
 
 def _signal_tree_parts(signal_name: str) -> tuple[str, ...]:
-    """Split dots and array indices into display hierarchy segments."""
+    """Split a result name into readable component, variable, and index levels.
+
+    OpenModelica emits state derivatives as names such as ``der(block.x)``.
+    Keep those traces available, but display them below a ``Derivatives`` group
+    on their owning component instead of creating a misleading top-level
+    ``der(block`` branch.
+    """
+
+    derivative = re.fullmatch(r"der\((.+)\)", signal_name)
+    if derivative is not None:
+        inner_name = derivative.group(1)
+        inner_parts = _signal_tree_parts(inner_name)
+        if inner_parts:
+            index_count = len(re.findall(r"\[[^\]]+\]", inner_name.rsplit(".", 1)[-1]))
+            variable_index = max(0, len(inner_parts) - index_count - 1)
+            return (
+                *inner_parts[:variable_index],
+                "Derivatives",
+                *inner_parts[variable_index:],
+            )
+        return ("Derivatives", signal_name)
 
     parts: list[str] = []
     for segment in signal_name.split("."):