Fix heat loop list scrolling and ordering

CHANGELOG.md

@@ -2,6 +2,7 @@
 ## Unreleased
 - Improved performance
   - Color animations no longer update all materials when they haven't changed.
+- Fixed the heat-loop list scroll content not expanding when a vessel has more loops than fit in the viewport.
 
 ## 0.9.1 - 2026-05-12
 - Fixed memory leaks from dangling event handlers.

Source/UI/ToolbarUI/ToolbarLoops.cs

@@ -120,6 +120,15 @@ void PollLoopWidgets(SystemHeatSimulator simulator)
           RecalculatePanelPositionData();
         }
       }
+
+      // Heat loops are discovered by walking vessel parts, so their creation
+      // order is not guaranteed to match their numeric IDs.  Keep the content
+      // order stable and predictable for the player.
+      loopPanelWidgets.Sort((left, right) => left.TrackedLoopID.CompareTo(right.TrackedLoopID));
+      for (int i = 0; i < loopPanelWidgets.Count; i++)
+      {
+        loopPanelWidgets[i].transform.SetSiblingIndex(i);
+      }
     }
     protected void RecalculatePanelPositionData()
     {
@@ -135,6 +144,11 @@ protected void RecalculatePanelPositionData()
       Utils.Log($"Source data: buttonYOffsetFromTop={buttonYOffsetFromTop }, loopPanelMaxHeight={loopPanelMaxHeight} widgetTotalHeight={widgetTotalHeight}", LogType.UI);
       //loopPanelWidgets.Count * 68f + vlg.padding.top+vlg.padding.bottom+ 3f+7.5f*(loopPanelWidgets.Count-1);
       loopPanelRootRect.SetSizeWithCurrentAnchors(RectTransform.Axis.Vertical, loopPanelMaxHeight);
+      // The ScrollRect content must contain the complete list.  Previously only
+      // the viewport was resized, leaving the content at its prefab height when
+      // more loops were added than could be shown at once.  That made some loop
+      // widgets unreachable or appear to be missing from the list.
+      loopPanelScrollRootRect.SetSizeWithCurrentAnchors(RectTransform.Axis.Vertical, widgetTotalHeight);
       loopPanelScrollViewportRect.anchorMin = loopPanelScrollBackground.anchorMin = new Vector2(0, 0);
       loopPanelScrollViewportRect.anchorMax = loopPanelScrollBackground.anchorMax = new Vector2(1, 0);
       loopPanelScrollCarat.anchorMin = new Vector2(0, 1);