I'm using Windows 10 and just updated to Firefox 78.0.1 last night. Normally, when I open a new tab, I push the down arrow key to bring up my browser history and access my most-used sites. Upon updating last night, I discovered that I can no longer do this. When I press the down key, nothing happens. To get the same result I'm used to, I have to press the space bar, but I've been doing this a certain way for several years and the motion is completely ingrained in me. If I turn Top Sites back on in the options, the drop-down list will open upon pressing the down key, but that of course only brings up the Top Sites. That's not what I want. I tried rolling back to the previous version, 77.0.1, but that didn't fix anything. If I create a new profile, the problem persists. Does anyone know how I can fix this? I know it sounds like an extremely minor issue, and maybe that's true, but I just want to use my browser the way I like using it. I'd appreciate any help/input.

Also, I suppose I should mention that I didn't make any changes to my preferences prior to this issue.