GtkTreeView breakage in master

[Tristan Van Berkom <tristanvb openismus com>]

First, sorry to write the list for something like this.

This would again be easier to fix on irc but, when I wake 
up and find things broken with git master, it just happens
that everyone else is sleeping.

I cant tell exactly where the breakage is coming from
but, to make a long story short... just fire up
./tests/testtreeedit (from git master) and resize the window.

It seems that the problem has something to do with the
recent gdk changes, dirty areas in the treeview seem to
miss out on getting redrawn (GdkWindow issues ?).

Here is a screenshot of the problem:
  http://people.gnome.org/~tvb/broken-testtreeedit.png
Usually there are supposed to be 4 rows of data, the
other rows disappear after resizing the window (oddly,
it seems they disappear only once the GtkCellRendererProgress
is shown)... mousing over the rows make the rows re-appear.

Also, it seems the buttons in the treeview columns (and
the rendered GtkCellRendererProgress) have lost their
"etched"ness, this part I am assuming is not a bug but
probably part of the result of Carlos's style context
work (probably I'm just seeing un-themed progress
renderers and treeviewcolumn buttons)...

Cheers,
     -Tristan