Select some text starting from the right and continue to select it all the way to the left until you hit the screen. I guess it's not really a bug it's just really annoying when you accidentally select too much and end up selecting the entire document

i clicked on the tick mark and didn't realise it would mark it as resolved. it isn't actually resolved! sorry

That was definitely a bug! Fixed for 0.1.1

By the way, you can un-resolve a thread by clicking on the tick again to toggle it off. The resolved tag doesn't immediately disappear -- refresh the page to see the change.