Due to a limitation in Zabbix DM setup, it is not possible to add slideshows with screens from different nodes (this should also be looked at)
A workaround for this is to create all slideshows AND screens on the master node.

For this to work you end up adding a bunch of graphs (stored on child nodes) on a screen (stored on the local node). So far so good, just a minor incovenience.

Here's where the issue starts:
Say you want to edit such a screen:

You decide the graph is too wide or should have a different column span or something like that. In a non-DM environment you just click the graph and change the width or column span or whatever. However with my DM setup, as soon as i click the graph, suddenly Zabbix forgets what graph was in that spot and you have to reselect it, going trough nodes, groups, and graphs again,
this is extremely annoying when calibrating width, height of such screens.

There's also a forum topic on this: http://www.zabbix.com/forum/showthread.php?t=22358