Missing test for null child in gtk_window_focus()

[Federico Mena Quintero <federico ximian com>]

In gtk_window_focus(), we have this:

  /* Now try to focus the first widget in the window */
  if (GTK_WIDGET_DRAWABLE (bin->child) &&
      GTK_WIDGET_IS_SENSITIVE (bin->child))
    {

However, the code never checks for bin->child != NULL.  This breaks
applications like XMMS that do something stupid^H^H^H^H^H^Hinteresting
with toplevel windows that do not have children.

The suggested patch is the attachment in this bug report:

	http://bugzilla.ximian.com/show_bug.cgi?id=2492

Since it is pretty obvious, may I write up a ChangeLog for it and
commit it?

  Federico