Crystal is a kwin window decoration theme which offers you (pseudo) transparent
titlebar, buttons and borders.  It also has some little usuability enhancements.

Main features:
* The style grabs your wallpaper and uses it as the deco background. 
  It has several blending modes, i.e. it can fade the background 
  into the defined title bar color, or it can brighten or darken 
  the wallpaper, as well as blur the source image to simulate glass.
* Choose the blending color of the buttons.
* You can define the title bar height and border size of the windows.
* Right click on minimize button toggles shade mode.
* Middle click on minimize button sends window to below.
* Double click on program symbol closes window.
* Support for button themes. Basic button theme is included, feel 
  free to swamp me with cool themes.
* Can show a tooltip of the caption
* Mouse-wheel on the title bar to 'scroll' to all opened windows of 
  the same desktop.