are you sure its just the guestbook? i've noticed funky and really hard to reproduce bugs around moving recently that are driving me up the wall.. wont work the first time, does the second.. etc.. can you dig deeper and figure out if its always reproduceble and if so with what/how?

No I only have it on the guestbook. but when I add more than 2 other blocks first then It works also with the guestbook. But now I tested it on 5.3.3 beta2.
in the 5.3.2 version I didn't checked that. I will do that now.

Now I noticed that only when I add the guestbook block to a page the whole move function doesn't save the right positions. even dragging other blocks into other red edit blocks won't save the made changes. But when I delete the guestbook and try to move the other block_items which are on that page. It does save the changed positions again.

It could be possible that other types of block lead to the same problems of not getting the changed location saved on a page. But then you'll have to find which blocktype of that page causes the problem. For example my guestbook block did. Furthermore I noticed that When you make a (new) empty page. and first add x (4,5,6) other block types and then add the guestbook the guestbook isn't saved when i move to another place. but when i move other blocks they do do change.

This issue should of been resolved long ago. Is it fixed in 5.4?

I note another thread about the same issue, still remaining unresolved:

http://www.concrete5.org/community/bugs/block_moving__reordering_fl...

Technical explanation can be found here:
http://www.concrete5.org/index.php?cID=30440...