diff --git a/gui/main.qml b/gui/main.qml
index a322df8..4df275c 100644
--- a/gui/main.qml
+++ b/gui/main.qml
@@ -97,14 +97,21 @@ ApplicationWindow {
 
     function buildSessionTree() {
         console.log("buildSessionTree: sessions count = " + ollie.sessions.length)
+        // Save expanded state before clearing
+        var expandedSessions = {}
+        for (var ei = 0; ei < sessionTreeModel.count; ++ei) {
+            var eitem = sessionTreeModel.get(ei)
+            if (eitem.type === "session" && eitem.expanded)
+                expandedSessions[eitem.id] = true
+        }
         sessionTreeModel.clear()
         var sessions = ollie.sessions
         for (var i = 0; i < sessions.length; ++i) {
             var sess = sessions[i]
             var sid = sess.id || ""
             console.log("  session[" + i + "] = " + sid)
-            // Auto-expand active session
-            var expanded = (sid === ollie.activeSessionId)
+            // Preserve previous expanded state; also auto-expand active session
+            var expanded = expandedSessions[sid] || (sid === ollie.activeSessionId)
             // Add session node
             sessionTreeModel.append({
                 type: "session",