Issue #15853: Prevent IDLE crash on OS X when opening Preferences menu

with certain versions of Tk 8.5.  Initial patch by Kevin Walzer.

Lib/idlelib/NEWS.txt

@@ -15,6 +15,9 @@ What's New in IDLE 2.7.4?
 - Issue #14018: Update checks for unstable system Tcl/Tk versions on OS X
   to include versions shipped with OS X 10.7 and 10.8 in addition to 10.6.
 
+- Issue #15853: Prevent IDLE crash on OS X when opening Preferences menu
+  with certain versions of Tk 8.5.  Initial patch by Kevin Walzer.
+
 
 What's New in IDLE 2.7.3?
 =========================

Lib/idlelib/configDialog.py

@@ -832,10 +832,9 @@ class ConfigDialog(Toplevel):
             fontWeight=tkFont.BOLD
         else:
             fontWeight=tkFont.NORMAL
-        size=self.fontSize.get()
-        self.editFont.config(size=size,
-                weight=fontWeight,family=fontName)
-        self.textHighlightSample.configure(font=(fontName, size, fontWeight))
+        newFont = (fontName, self.fontSize.get(), fontWeight)
+        self.labelFontSample.config(font=newFont)
+        self.textHighlightSample.configure(font=newFont)
 
     def SetHighlightTarget(self):
         if self.highlightTarget.get()=='Cursor': #bg not possible