The last screenshot is standard information from your program. I just rewrite all tray->showMessage to my Notification::instance->notify. For now I have biggest problems with this icons. Temporary I have hardcoded them, but in future they need to be get from system directories.

About replacing all QMessageBox into notify, I also think that it isn't good idea. There are sometimes such situations when user must know that program want answer from him. But many messages can be done my path. For example information about changing status of transaction (from unknown to confirmed).