[For 1.8] Thank You/Like System v3.3.6 + MyAlerts support

[Eldenroot]

I think that popup is an overkill for a "simple" user action and also adds the need to customize its appearance to match the forum theme/style.

The style for popup alerts is used from MyBB default css style for popups messages so feel free to customize it it has nothing to do with Thank you/like plugin. Our plugin uses style used in MyBB