Various mesh behaviors from a Tkinter inherited text element

In another answer here, the user created an inherited TextWithVar class that provides instances of the Tkinter.Text element, but with a text variable like Tkinter.Entry. However, when testing, this new class behaves differently than the Text element when using the Grid manager. To demonstrate, this code is copied from this answer, with some test calls added at the end:

import Tkinter as tk

class TextWithVar(tk.Text):
    '''A text widget that accepts a 'textvariable' option'''
    def __init__(self, parent, *args, **kwargs):
        try:
            self._textvariable = kwargs.pop("textvariable")
        except KeyError:
            self._textvariable = None

        tk.Text.__init__(self, *args, **kwargs)

        # if the variable has data in it, use it to initialize
        # the widget
        if self._textvariable is not None:
            self.insert("1.0", self._textvariable.get())

        # this defines an internal proxy which generates a
        # virtual event whenever text is inserted or deleted
        self.tk.eval('''
            proc widget_proxy {widget widget_command args} {

                # call the real tk widget command with the real args
                set result [uplevel [linsert $args 0 $widget_command]]

                # if the contents changed, generate an event we can bind to
                if {([lindex $args 0] in {insert replace delete})} {
                    event generate $widget <<Change>> -when tail
                }
                # return the result from the real widget command
                return $result
            }
            ''')

        # this replaces the underlying widget with the proxy
        self.tk.eval('''
            rename {widget} _{widget}
            interp alias {{}} ::{widget} {{}} widget_proxy {widget} _{widget}
        '''.format(widget=str(self)))

        # set up a binding to update the variable whenever
        # the widget changes
        self.bind("<<Change>>", self._on_widget_change)

        # set up a trace to update the text widget when the
        # variable changes
        if self._textvariable is not None:
            self._textvariable.trace("wu", self._on_var_change)

    def _on_var_change(self, *args):
        '''Change the text widget when the associated textvariable changes'''

        # only change the widget if something actually
        # changed, otherwise we'll get into an endless
        # loop
        text_current = self.get("1.0", "end-1c")
        var_current = self._textvariable.get()
        if text_current != var_current:
            self.delete("1.0", "end")
            self.insert("1.0", var_current)

    def _on_widget_change(self, event=None):
        '''Change the variable when the widget changes'''
        if self._textvariable is not None:
            self._textvariable.set(self.get("1.0", "end-1c"))

root = tk.Tk()
text_frame = TextWithVar(root)
text_frame.grid(row=1, column=1)
test_button = tk.Button(root, text='Test')
test_button.grid(row=1, column=1, sticky='NE')
root.mainloop()

root2 = tk.Tk()
frame = tk.Frame(root2)
frame.grid(row=1, column=1)
text_frame2 = TextWithVar(frame)
text_frame2.grid(row=1, column=1)
test_button2 = tk.Button(frame, text='Test')
test_button2.grid(row=1, column=1, sticky='NE')
root2.mainloop()

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