W32: Fix listbox selection

W32: Fix listbox selection

* Makes listbox background white instead of default grey
* Uses gradients or W32 theme parts to draw sexy selection/prelight
  rectangle instead of changing selected/prelighted item background
* Removes blanket button text color, allowing buttons to inherit
  text color from their parents. Non-normal buttons DO get specific
  text color though. This partially fixes text color propagation from
  listbox rows to their children.

https://bugzilla.gnome.org/show_bug.cgi?id=727244