Transparent window title bar

Solution 1:

This is a partial solution, as I couldn't figure out why it doesn't work for active window.

As mentioned by chaskes, decoration transparency now is defined by themes using CSS (property or external background image).

Tested with Ambiance theme:

• modified

  /usr/share/themes/Ambiance/gtk-3.0/apps/unity.css
  

• by commenting background-image of UnityDecoration.top and UnityDecoration.top:backdrop leaving background-color: transparent;

  UnityDecoration.top {
      ...
      background-color: transparent;
      ...
      /*
      background-image: -gtk-gradient (linear, left top, left bottom,
                                       from (shade (@dark_bg_color, 1.5)),
                                       to (shade (@dark_bg_color, 1.04)));
      */
      ...
  }
  
  UnityDecoration.top:backdrop {
      ...
      background-color: transparent;
      ...
      /*
      background-image: -gtk-gradient (linear, left top, left bottom,
                                       from (shade (#474642, 0.92)),
                                       to (@dark_bg_color));
      */
  }