# -*- coding: utf-8 -*-
import gtk
from xlutils.copy import copy
from xlrd import open_workbook

def b_click (b):
    print text.get_buffer().insert_at_cursor(sheet.cell_value(0,0))
w = gtk.Window(gtk.WINDOW_TOPLEVEL)
w.set_size_request(300, 200)
w.set_border_width(10)
w.connect("destroy", quit)
b = gtk.Button("View")
b.connect('clicked', b_click)
b.show()
text = gtk.TextView()
buffer = gtk.TextBuffer()
text.set_justification(gtk.JUSTIFY_CENTER)
text.set_wrap_mode(gtk.WRAP_WORD_CHAR)

rb = open_workbook('7.xls')
sheet = rb.sheet_by_index(0)

t = gtk.Table(5, 5, True)
t.attach(b, 1, 2, 3, 5)
t.attach(text, 0, 5, 0, 3)
w.add(t)
t.show()
w.show_all()

gtk.main()

TypeError: GtkTextBuffer.insert_at_cursor() argument 1 must be string or read-only buffer, not float

 print text.get_buffer().insert_at_cursor(sheet.cell_value(0,0))

def b_click1 (b):
    ptext=text_from_clipboard()
    wb.get_sheet(0).write(0,0,ptext)
    os.remove('1.xls')
    wb.save('1.xls')
def text_from_clipboard():
    clipboard=gtk.Clipboard(display=gtk.gdk.display_get_default(), selection="CLIPBOARD")
    start, end = buffer.get_bounds()
    buffer.select_range(start, end)
    ptext=text.get_buffer().copy_clipboard(clipboard)
    ptext=clipboard.wait_for_text()
    clipboard.store()    
    return ptext