public void addContent(WindowSectionContent content, AddContentCallback callback) {
AddContentCallback safeCallback = (callback != null) ? callback : new AddContentCallbackAdapter() { /**/ };
if (idToContent.containsKey(content.getId())) {
// The content has already been added. Make it active:
setActiveContent(content);
safeCallback.contentAdded(this, content);
} else {
Runnable job = new AddContentJob(content, safeCallback);
new BusyWorker(getWindow(), job).run();
}
}