Please describe the problem:
I display a large amount of text in a restricted space, so I use set_width() and set_ellipsize() to let pango cut the text. It works fine, except when the line is very large, then the text escapes its boundaries.

Steps to reproduce:
Here is a minimal testcase in pygtk:

import gtk
import pango
from random import random
import cairo

#SIZE = 1000 # Good
SIZE = 15000 # Bad

class Widget(gtk.DrawingArea):
    def __init__(self):
        gtk.DrawingArea.__init__(self)
        self.connect('expose-event', type(self).expose_event)
        self.modify_font(pango.FontDescription('Monospace 24'))

    def expose_event(self, event):
        context = self.window.cairo_create()
        text = '<' + str(random()) * SIZE + '>'
        pl = self.create_pango_layout(text)
        pl.set_width(int(self.allocation.width * pango.SCALE))
        pl.set_ellipsize(pango.ELLIPSIZE_MIDDLE)
        context.set_source_rgb(random(), random(), random())
        context.show_layout(pl)
        return False

win = gtk.Window()
box =  gtk.HBox()
for i in xrange(4):
    box.add(Widget())
win.add(box)
win.show_all()
gtk.main()


Actual results:
With, the SIZE set to 1000, it works fine. Resizing the window show the ellipsize effect. With SIZE set to 15000, the display is garbled. By the way, in both cases, the speed is quite slow. It is expected, because of the size of the buffer, but I wouldn't mind if it was faster ;-)

Expected results:
With SIZE set to 15000, the display should be similar to the one with SIZE set to 1000.

Does this happen every time?
Yes.

Other information: