diff -r d3cb8720f17e Lib/idlelib/EditorWindow.py
--- a/Lib/idlelib/EditorWindow.py	Tue Nov 20 16:13:54 2012 +0200
+++ b/Lib/idlelib/EditorWindow.py	Tue Nov 20 23:52:18 2012 +0200
@@ -170,13 +170,13 @@
                 'recent-files.lst')
         self.text_frame = text_frame = Frame(top)
         self.vbar = vbar = Scrollbar(text_frame, name='vbar')
-        self.width = idleConf.GetOption('main','EditorWindow','width')
+        self.width = idleConf.GetOption('main','EditorWindow','width', type='int')
         text_options = {
                 'name': 'text',
                 'padx': 5,
                 'wrap': 'none',
                 'width': self.width,
-                'height': idleConf.GetOption('main', 'EditorWindow', 'height')}
+                'height': idleConf.GetOption('main', 'EditorWindow', 'height', type='int')}
         if TkVersion >= 8.5:
             # Starting with tk 8.5 we have to set the new tabstyle option
             # to 'wordprocessor' to achieve the same display of tabs as in
@@ -253,7 +253,8 @@
         if idleConf.GetOption('main', 'EditorWindow', 'font-bold', type='bool'):
             fontWeight='bold'
         text.config(font=(idleConf.GetOption('main', 'EditorWindow', 'font'),
-                          idleConf.GetOption('main', 'EditorWindow', 'font-size'),
+                          idleConf.GetOption('main', 'EditorWindow',
+                                             'font-size', type='int'),
                           fontWeight))
         text_frame.pack(side=LEFT, fill=BOTH, expand=1)
         text.pack(side=TOP, fill=BOTH, expand=1)
@@ -766,7 +767,8 @@
         if idleConf.GetOption('main','EditorWindow','font-bold',type='bool'):
             fontWeight='bold'
         self.text.config(font=(idleConf.GetOption('main','EditorWindow','font'),
-                idleConf.GetOption('main','EditorWindow','font-size'),
+                idleConf.GetOption('main','EditorWindow','font-size',
+                                   type='int'),
                 fontWeight))
 
     def RemoveKeybindings(self):
diff -r d3cb8720f17e Lib/idlelib/FormatParagraph.py
--- a/Lib/idlelib/FormatParagraph.py	Tue Nov 20 16:13:54 2012 +0200
+++ b/Lib/idlelib/FormatParagraph.py	Tue Nov 20 23:52:18 2012 +0200
@@ -32,7 +32,8 @@
         self.editwin = None
 
     def format_paragraph_event(self, event):
-        maxformatwidth = int(idleConf.GetOption('main','FormatParagraph','paragraph'))
+        maxformatwidth = int(idleConf.GetOption('main','FormatParagraph',
+                                                'paragraph', type='int'))
         text = self.editwin.text
         first, last = self.editwin.get_selection_indices()
         if first and last:
diff -r d3cb8720f17e Lib/idlelib/configDialog.py
--- a/Lib/idlelib/configDialog.py	Tue Nov 20 16:13:54 2012 +0200
+++ b/Lib/idlelib/configDialog.py	Tue Nov 20 23:52:18 2012 +0200
@@ -936,7 +936,7 @@
             self.listFontName.select_anchor(currentFontIndex)
         ##font size dropdown
         fontSize=idleConf.GetOption('main','EditorWindow','font-size',
-                default='10')
+                type='int', default='10')
         self.optMenuFontSize.SetMenu(('7','8','9','10','11','12','13','14',
                 '16','18','20','22'),fontSize )
         ##fontWeight
@@ -1022,10 +1022,13 @@
         self.autoSave.set(idleConf.GetOption('main', 'General', 'autosave',
                                              default=0, type='bool'))
         #initial window size
-        self.winWidth.set(idleConf.GetOption('main','EditorWindow','width'))
-        self.winHeight.set(idleConf.GetOption('main','EditorWindow','height'))
+        self.winWidth.set(idleConf.GetOption('main','EditorWindow','width',
+                                             type='int'))
+        self.winHeight.set(idleConf.GetOption('main','EditorWindow','height',
+                                              type='int'))
         #initial paragraph reformat size
-        self.paraWidth.set(idleConf.GetOption('main','FormatParagraph','paragraph'))
+        self.paraWidth.set(idleConf.GetOption('main','FormatParagraph','paragraph',
+                                              type='int'))
         # default source encoding
         self.encoding.set(idleConf.GetOption('main', 'EditorWindow',
                                              'encoding', default='none'))
diff -r d3cb8720f17e Lib/idlelib/configHandler.py
--- a/Lib/idlelib/configHandler.py	Tue Nov 20 16:13:54 2012 +0200
+++ b/Lib/idlelib/configHandler.py	Tue Nov 20 23:52:18 2012 +0200
@@ -238,24 +238,39 @@
         printed to stderr.
 
         """
-        if self.userCfg[configType].has_option(section,option):
-            return self.userCfg[configType].Get(section, option,
-                                                type=type, raw=raw)
-        elif self.defaultCfg[configType].has_option(section,option):
-            return self.defaultCfg[configType].Get(section, option,
-                                                   type=type, raw=raw)
-        else: #returning default, print warning
-            if warn_on_default:
-                warning = ('\n Warning: configHandler.py - IdleConf.GetOption -\n'
-                           ' problem retrieving configuration option %r\n'
-                           ' from section %r.\n'
-                           ' returning default value: %r\n' %
-                           (option, section, default))
-                try:
-                    sys.stderr.write(warning)
-                except IOError:
-                    pass
-            return default
+        try:
+            if self.userCfg[configType].has_option(section,option):
+                return self.userCfg[configType].Get(section, option,
+                                                    type=type, raw=raw)
+        except ValueError:
+            warning = ('\n Warning: configHandler.py - IdleConf.GetOption -\n'
+                       ' invalid %r value for configuration option %r\n'
+                       ' from section %r: %r\n' %
+                       (type, option, section,
+                        self.userCfg[configType].Get(section, option,
+                                                     raw=raw)))
+            try:
+                sys.stderr.write(warning)
+            except IOError:
+                pass
+        try:
+            if self.defaultCfg[configType].has_option(section,option):
+                return self.defaultCfg[configType].Get(section, option,
+                                                       type=type, raw=raw)
+        except ValueError:
+            pass
+        #returning default, print warning
+        if warn_on_default:
+            warning = ('\n Warning: configHandler.py - IdleConf.GetOption -\n'
+                       ' problem retrieving configuration option %r\n'
+                       ' from section %r.\n'
+                       ' returning default value: %r\n' %
+                       (option, section, default))
+            try:
+                sys.stderr.write(warning)
+            except IOError:
+                pass
+        return default
 
     def SetOption(self, configType, section, option, value):
         """In user's config file, set section's option to value.