@tmxretro the "h" key is the default retroarch "reset content" hotkey and, without a controller connected, there is no default "enable hotkey" hotkey configured, so all the other ones (like "reset content") will work on their own, with just a single keypress.
You can toggle game focus with the "game focus (toggle)" hotkey (default: scroll_lock, configurable from settings > input > hotkeys > game focus (toggle)). While game focus is enabled, other hotkeys (including "exit emulator") will not function, passing full keyboard control to the loaded core; press scroll_lock again to disable game focus and return hotkey functionality.