Bug 12523 Paste in Packages does not accept files on the clipboard
I created a FileTransfer in another view that contains file paths and placed it on the clipboard using SWT DND Clipboard object. Resource navigator recognized this and allowed me to paste the files into the project, but Packages 'Paste' didn't.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/reorg/PasteResourcesFromClipboardAction.java
}
	
	private boolean canOperateOn(IStructuredSelection selection){
		IResource[] resourceData= getClipboardResources();
		if (resourceData == null || resourceData.length == 0)
			return false;
			
		if (ClipboardActionUtil.isOneOpenProject(resourceData))
			return true;
			
		if (selection.size() != 1) 
			return false;
		
		/*
		 * special case: if both source references and resources are in clipboard - disable this action
		 * if a compilation unit is selected.
		 * this is important in the case when a type is copied to the clipboard - we put also its compilation unit
		 */
		TypedSource[] typedSource= getClipboardSourceReference();
		if (selection.getFirstElement() instanceof ICompilationUnit && typedSource != null && typedSource.length != 0)
			return false;
		
		if (StructuredSelectionUtil.getResources(selection).length != 1)
			return false;
		
		if (resourceData == null)
			return ClipboardActionUtil.getFirstResource(selection) instanceof IContainer;	
		
		return canActivateCopyRefactoring(resourceData, ClipboardActionUtil.getFirstResource(selection));
	}