fix issue where building stats don't update while the building is kept selected

src/ui/SelectedBuildingPanel.cpp

@@ -188,6 +188,11 @@ void SelectedBuildingPanel::buildSingle(EntityId id)
         m_clearBeltBtn->hide();
     }
 
+    refreshBuffers(b);
+}
+
+void SelectedBuildingPanel::refreshBuffers(const Building* b)
+{
     QString bufText;
     if (!b->inputBuffer.counts.empty())
     {
@@ -221,6 +226,18 @@ void SelectedBuildingPanel::buildSingle(EntityId id)
     m_buffersLabel->setText(bufText);
 }
 
+void SelectedBuildingPanel::onStateUpdated(Tick /*tick*/, int /*blocks*/, double /*speed*/)
+{
+    if (m_singleId == kInvalidEntityId) { return; }
+    const Building* b = m_sim->buildings().findBuilding(m_singleId);
+    if (!b)
+    {
+        buildEmpty();
+        return;
+    }
+    refreshBuffers(b);
+}
+
 void SelectedBuildingPanel::buildMulti(const std::vector<EntityId>& ids)
 {
     m_singleId = kInvalidEntityId;