[news.eclipse.tools] resource tree is locked?

[bob.donovan@xxxxxxxx (Bob Donovan)]

Hi,

I am trying to implement a feature where a user can drop an existing
source on a Folder in the workbench, and my plugin will parse it and
reconcile the statements into the internal model.

Upon some reading, I found that the way to do this was by implementing a
org.eclipse.core.resources.IResourceChangeListener in combination with a
IResourceDeltaVisitor. 

When I drop a source file onto the workspace, I can reconcile it, but when
I try to add IMarkers.... I get the following error about the resource
tree being locked???

org.eclipse.core.internal.resources.ResourceException: The resource tree
is locked for modifications.

How do I implement this type of functionality? Can I unlock the tree? I
believe that the JDT is doing the same type of thing. I have been
searching in the source on how the JDT did this, but I haven't turned
anything up yet?

Bob