* remove shadow from plugin. This causes the plugin window to be dirty,
  find out why

* disable double buffering for the plugin with GTK+ API?

* remove black border in upper and left corners of the plugin window

* try to implement size negotiations with the plugin that sends javascript
  to the browser.

* access object's attribute and <PARAM> children. Jean claims he does
  this already, but the code seems to access GLib properties only,
  no external params

* implement a size negotiation mechanism from the plugin using 
  javascript. The plugin understands its ID from the object element,
  calculates the size and sends a URL with a javascript call to a function
  that sets width, height attributes of the object element