data containers

[Moritz]

Another (more practical) question:

Im trying to use a two dimensional array for my ScreenElements:

ScreenElement[][] layer_map;

Then, Id like to itereate over all the ScreenElements in this array, but 
I get syntax errors in the inner foreach-loop, on the single_layer 
identifier.

Errormessage: Syntax error on token "single_layer", ; expected after 
this token

foreach(ScreenElement[] single_layer; layer_map[][])
{
	foreach(ScreenElement element, single_layer)
	{
		element.display();
	}
}

Can anyone tell me how to do this correctly?