Applying attribute appendTo to the dropdown element does not have any connection to the original ui-dropdown container element.
This means when we want to style a different look to a dropdown, we cannot apply the same style to its ui-dropdown-panel element since it is attached for instance to the body and they have no custom class on them.
This is why, we have to introduce panelStyleClass to make sure we can collaborate with the original ui-dropdown element.
Attribute panelStyle is very useful when we want to apply a custom width or any other style to ui-dropdown-panel element when appendTo is also applied.
Added panelStyle and panelStyleClass attributes to dropdown component