I'll create a dropdown component for countries organized by continent with checkboxes and a select all option.

This country dropdown component includes:

1. Continent Organization: Countries are grouped by continent (Europe, North America, Asia, etc.)

2. Checkbox Selection:

   • Individual country checkboxes
   • "Select All" checkbox for all countries
   • Continent-level "Select All" checkboxes for each continent
3. Search Functionality: Filter countries by name as you type

4. Selection Status:

   • Shows the number of selected countries
   • Checkboxes have three states: checked, unchecked, and indeterminate (when some items in a group are selected)
5. Responsive Design: Works well on different screen sizes

The component is fully interactive - you can:

• Open/close the dropdown
• Search for specific countries
• Select individual countries
• Select/deselect all countries in a continent
• Select/deselect all countries globally

You can use this component in any Next.js application by importing it into your page or layout.