Closing the dropdown when clicking outside of it

[dzhavat]

Right now, the only way to close the dropdown list is by clicking again on the button.

It'd be nice if the dropdown could close when clicking outside of it. That'd also make it behave similarly to all other dropdowns on GitHub.

[fregante]

This is best implemented by copying the native <details> implementation that other GitHub buttons have. You can copy the whole Filter dropdown and also fix this other issue in one go: #8

[dzhavat]

Nice! Will give it a try 👍