diff --git a/init.go b/init.go
index e549b18..291020c 100644
--- a/init.go
+++ b/init.go
@@ -376,6 +376,7 @@ func refreshGocui() {
 			// artificially pause clock while dragging.
 			// this is a reminder to make this refresh code smarter
 			// after the switch to protocol buffers
+			me.myTree.Lock()
 			if me.mouse.mouseUp {
 				// log.Info("refresh now on mouseUp")
 				// todo: add logic here to see if the application has changed anything
@@ -387,6 +388,7 @@ func refreshGocui() {
 					lastRefresh = time.Now()
 				}
 			}
+			me.myTree.Unlock()
 		}
 	}
 }
@@ -402,6 +404,7 @@ func newWindowTrigger() {
 			// log.Log(NOW, "newWindowTrigger() got new window", tk.cuiName)
 			// time.Sleep(200 * time.Millisecond)
 			waitOK()
+			me.myTree.Lock()
 			// time.Sleep(200 * time.Millisecond)
 			redoWindows(me.FirstWindowW, me.FirstWindowH)
 			me.firstWindowOk = true
@@ -414,6 +417,7 @@ func newWindowTrigger() {
 				me.textbox.tk.prepTextbox()
 			}
 			tk.makeWindowActive()
+			me.myTree.Unlock()
 		}
 	}
 }