Began  writing  a  window  manager from scratch. Quickly realized that
  this topic sucks. Java sucks, too.

  There's too much broken stuff out there.

  I now understand what people mean by saying, "there's no such thing as
  a  simple  window  manager". Window managers are inevitably complex if
  they are to do things -- more or less -- correctly.

  As for Java: It does not account for X  window  borders.  I  mean  the
  plain  borders  that  "simple"  WMs like dwm use. That's why menus are
  misaligned. Moreover, things are NOT automatically fixed  if  your  WM
  does reparenting. Ugh.

  I  don't  think  it's  entirely Java's fault, though. You see, there's
  non-reparenting WMs, reparenting WMs, double-reparenting WMs,  there's
  ICCCM,  there's  EWMH, ... Then there's multi-screen setups and multi-
  monitor setups. All kinds of weird stuff. I'm not surprised that  they
  don't get it right.