public boolean isLoaded() {
		return (viewComposite != null);
	}
Returns whether or not the editor has a structure loaded.  If no structure is loaded then
only unload() or dispose() methods should be called.

@return true if an editable structure is currently loaded in the model.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/compositeeditor/CompositeViewerModel.java