[BUG] Clicks on coordinate 0,0 with mouse aren't registered

### Version of Kakoune e569dce8ff6c10840654e011167c550c014ef776 ### Reproducer - Run `kak -n` - Press i and write `hello`. Press `esc` to enter normal mode - Try to click on the "h" -> Cursor **doesn't** move to the h as expected - Click on the "e" -> Cursor moves to the e, as expected ### Outcome Nothing happens ### Expectations Cursor should move to the h when clicked on ### Additional information * I'm running on the newest commit (e569dce8ff6c10840654e011167c550c014ef776)