diff --git a/mode/__init__.py b/mode/__init__.py
index 458ac25..0ab1551 100644
--- a/mode/__init__.py
+++ b/mode/__init__.py
@@ -466,6 +466,7 @@ class Fundamental(Handler):
 
     def region_added(self, p, newlines):
         mname = self.name
+
         if self.lexer is not None:
             ydelta = len(newlines) - 1
             xdelta = len(newlines[-1])
@@ -487,12 +488,11 @@ class Fundamental(Handler):
                     ghist.setdefault(name, {})
                     ghist[name][newp] = self.ghist[name][gp]
             self.ghist = ghist
+
         if self.tabber is not None:
             self.tabber.region_added(p, newlines)
         if self.context is not None:
             self.context.region_added(p, newlines)
-        if self.lmargin != 0:
-            self.enable_line_numbers()
 
     def region_removed(self, p1, p2):
         if self.lexer is not None:
@@ -522,7 +522,5 @@ class Fundamental(Handler):
             self.tabber.region_removed(p1, p2)
         if self.context is not None:
             self.context.region_removed(p1, p2)
-        if self.lmargin != 0:
-            self.enable_line_numbers()
 
 install = Fundamental.install
diff --git a/mode/hex.py b/mode/hex.py
index d2223df..c9e8255 100644
--- a/mode/hex.py
+++ b/mode/hex.py
@@ -122,10 +122,17 @@ class HexOverwriteChar(Method):
             hb = w.application.methods['hex-backward']
             (cx, cy) = w.cursor.xy()
             ix = b.cursorx_to_datax(cy, cx)
+            if ix is None:
+                return
+            lm1 = w.mode.lmargin
             cx2 = w.buffer.datax_to_cursorx(ix)
             w.goto(Point(cx2, cy))
+            lm2 = w.mode.lmargin
             w.overwrite_char_at_cursor(self.part1)
+            lm3 = w.mode.lmargin
             w.overwrite_char_at_cursor(self.part2)
+            lm4 = w.mode.lmargin
+            w.set_error('%r/%r/%r/%r' % (lm1, lm2, lm3, lm4))
         elif self.char not in string.hexdigits:
             return
         else:
@@ -219,8 +226,8 @@ class Hex(mode.Fundamental):
     config = {
         'hex.disinst': 'disinst',
     }
-    lmargin    = 12
-    rmargin    = 18
+    #lmargin    = 12
+    #rmargin    = 18
     _ctrans    = ['.'] * 256
     byteorder  = 'native'
     byteorders = {
@@ -240,8 +247,8 @@ class Hex(mode.Fundamental):
                HexOverwriteCharSpace, HexOverwriteCharTab,
                HexOverwriteCharNewline, HexGotoBeginning, HexGotoEnd]
 
-    header      = 1
-    header_size = 1
+    #header      = 1
+    #header_size = 1
     hlo = color.build('red', 'default')
     hhi = color.build('default', 'red')
     format = "%(flag)s  %(bname)-18s  (%(mname)s)  {%(symbolic)s}  %(cursor)s  %(perc)s"
@@ -272,6 +279,11 @@ class Hex(mode.Fundamental):
         mode.Fundamental.__init__(self, w)
         self.bindings = {}
 
+        self.lmargin = 12
+        self.rmargin = 18
+        self.header = 1
+        self.footer = 0
+
         self.add_bindings('center-view', ('C-l',))
         self.add_bindings('next-line', ('C-n', 'D_ARROW',))
         self.add_bindings('previous-line', ('C-p', 'U_ARROW',))
diff --git a/render.py b/render.py
index a5f992e..4fb1d21 100644
--- a/render.py
+++ b/render.py
@@ -35,7 +35,8 @@ class RenderString(object):
                 s = '%-*s' % (x2 - x, self.string)
             else:
                 s = self.string
+            assert self.x + x != 115
             cwin.addstr(self.y + y, self.x + x, s, self.attrs)
         except:
-            v = (y, self.x, x, self.string, self.attrs)
-            raise Exception, "cwin.addstr(%d, %d + %d, %r, %r) failed" % v
+            v = (self.y, y, self.x, x, self.string, self.attrs)
+            raise Exception, "cwin.addstr(%d + %d, %d + %d, %r, %r) failed" % v