[Mackx]

I got an extra hint from Auroux on how to translate the coordinates that xournal uses internaly to screen coordinates. This allowed me to use the erscribble-library, which is the same one used for scribbling on pdfs.
However:
- Sometimes it hangs the DR (seems to be related with pressing a up/down button, which causes a full refresh of the screen and scribbling at the same time, but I am not sure!) and you will loose everything!
- I only use the mechanism for strokes, so if you are using the feature that recognises squares and circles, updates will only come after a while.
- I only 'played' with it for a very short period, it works on multiple pages and when zoomed in, but I did not test it extensively.
- I noticed that the 'native DR menu' disappears after you have selected an other program and switch back to Xournal again. mxSudoku does not have this problem, so I must have messed-up something in the menu for xournal. (Edit: Found problem, should react on activateWindow-call when it is send on the D-Bus. Update will follow next weekend.)

I consider this an experimental version, use at your OWN RISK! It will be less stable then previous versions! Don't blame me for losing your drawings/scribbles!

Please give me your feedback certainly with respect to features of xournal that are not 'responsive' anymore with this latest change(s).