Bug 302441 [LinkedResources][CommonNavigator] When to show "Files and Folders Operation" dialog on drop
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/dialogs/ImportTypeDialog.java
IDEWorkbenchPlugin.IDE_WORKBENCH,
			"$nl$/icons/full/ovr16/virt_ovr.gif")}; 
		CompositeImageDescriptor virtualFolderDescriptor = new OverlayIcon(folderDescriptor, virtualFolderOverlayMap, new Point(16, 16)); 
		fileImage = fileDescriptor.createImage();
		
		linkedFileImage = linkedFileDescriptor.createImage();
		CompositeImageDescriptor desc = new AlignedCompositeImageDescriptor(fileDescriptor, folderDescriptor);
		folderAndFileImage = desc.createImage();
		desc = new AlignedCompositeImageDescriptor(linkedFileDescriptor, virtualFolderDescriptor);
		virtualFolderAndFileImage = desc.createImage();
		desc = new AlignedCompositeImageDescriptor(linkedFileDescriptor, linkedFolderDescriptor);
		linkedFolderAndFileImage = desc.createImage();
		
		IPreferenceStore store = IDEWorkbenchPlugin.getDefault().getPreferenceStore();
		if (store.getBoolean(IDEInternalPreferences.IMPORT_FILES_AND_FOLDERS_RELATIVE))
			variable = preferredVariable;
	}
	
	/* (non-Javadoc)
	 * @see org.eclipse.jface.dialogs.TrayDialog#close()
	 */
	public boolean close() {
		fileImage.dispose();
		linkedFileImage.dispose();
		folderAndFileImage.dispose();
		virtualFolderAndFileImage.dispose();
		linkedFolderAndFileImage.dispose();
		return super.close();
	}