Streamtuner2 may still crash randomly when changing channel tabs.

<b><pre style="background:#ff9999">Gdk:ERROR:/build/buildd/gtk+2.0-2.24.23/gdk/gdkregion-
generic.c:1110:miUnionNonO: assertion failed: (y1 < y2)</pre></b>

  *  Hard to reproduce, happens somewhat rarely.
  *  Only happens on mouse interaction, not <key>↓</key> <key>↑</key> interaction.
  *  More prevalent after startup. Albeit I've noticed it once with lengthier residence of ST2.

It's still hard to tell where this arises from.

  *  Certainly related to threading. Doesn't happen in --nt mode.
  *  The window title updating may be one cause.
  *  More likely is the current_category() selection or initial drawing in channels/__init__ though.
  *  Columns() doesn't seem to be the cause. It's uikit.do() wrapped consistently now.