Ok - applet itself occupies some space on the screen. So it's nice to stay within this and only this space with controls and configuration. No additional windows - applet changes it's face. It's all within it's space and as I said - when size is highly configurable - this kind of behaviour looks rather impossible to apply. This means "simple" for this kind of things at least for me. The worst case scenario is (imo) applet setting via control panel. Maybe because applet for me means something like "almost application" - something tiny.