Metro Button WP Plugin combines several buttons together: one main and up to 3 additional small buttons. Additionally, you can use the buttons as notification indicators. You receive separate event for each sub-button when user clicks on them. Look of the Metro Button WP is fully customizable – you can set the icons, texts, color, font, size, etc. of the main and additional buttons. Also you can change the count and location of the small buttons.
You can see the complete documentation here.
