diff --git a/bin/curvecalc b/bin/curvecalc
--- a/bin/curvecalc
+++ b/bin/curvecalc
@@ -237,7 +237,7 @@ def sub_commands_tk(master, curveset, su
 
     tk.Button(f, text="reload subs (C-r)", 
         command=reload_subs).pack(side='left')
-    tk.Button(f,text="new subterm named:", command=add_cmd).pack(side='left')
+    tk.Label(f, text="new subterm named:").pack(side='left')
     entry = tk.Entry(f, textvariable=newname)
     entry.pack(side='left', fill='x', exp=1)
     entry.bind("<Key-Return>", lambda evt: add_cmd())
diff --git a/light9/curve.py b/light9/curve.py
--- a/light9/curve.py
+++ b/light9/curve.py
@@ -315,14 +315,17 @@ class Curvesetview(tk.Frame):
         
         f = tk.Frame(self,relief='raised',bd=1)
         f.pack(side='top',fill='x')
-        b = tk.Button(f, text="new curve named:",
-                      command=lambda:
-                      self.curveset.new_curve(self.newcurvename.get()))
-        b.pack(side='left')
+        tk.Label(f, text="new curve named:").pack(side='left')
         
         self.newcurvename = tk.StringVar()
-        tk.Entry(f,textvariable=self.newcurvename).pack(side='left',
-                                                        fill='x',exp=1)        
+
+        def new_curve(event):
+            self.curveset.new_curve(self.newcurvename.get())
+            self.newcurvename.set('')
+        
+        entry = tk.Entry(f, textvariable=self.newcurvename)
+        entry.pack(side='left', fill='x',exp=1)        
+        entry.bind("<Key-Return>", new_curve)
         
         dispatcher.connect(self.add_curve,"add_curve",sender=self.curveset)