Fullscreen is not actually fullscreen

With the new setting of selecting running Minecraft Bedrock edition via windows at fullscreen,  my cursor moves off of the main game onto my desktop.  This is not "true fullscreen" in fact this is fullscreen border mode.  A true fullscreen you cannot move your cursor off the selected game/screen onto anything else, even your second monitor.

I do not have a second monitor and am running Win 10.