Just for your information, when you add a device to an already created dashboard, the new box is automatically placed at the bottom of the screen, which is normal, but it blocks the dropdown lists for selecting rooms and/or features. When these lists are long, the last items in the list cannot be selected (you cannot scroll the screen to bring it back up). You then have to move the box up to restore normal dropdown behavior.
My screen resolution is 1920x1080
I’ve noticed the same thing on my side; it’s sometimes annoying depending on what you want to display in the box.
Furthermore, on mobile this is compounded by having to scroll all the way to the bottom of the page to find the button, tap it, then scroll back up a bit blindly to find the new box to configure.
My 2 cents (I don’t know if this aligns with Gladys dev rules) would be to use something like a modal that opens in the middle with the box to configure and just a choice to say whether you want to put it in column 1, 2, or 3.
With a modal there’s no need to scroll all over the place.
Any thoughts on that @pierre-gilles?
I confirm
Indeed, it’s a bug that was reported by @gaetanb76 last month 
(Dashboard - Bug d'affichage quand on ajoute un appareil : box trop petite · Issue #1714 · GladysAssistant/Gladys · GitHub)
I made a PR that fixes the issue: Fix #1714: When editing device in room box, select should not be hidden behind bottom bar by Pierre-Gilles · Pull Request #1732 · GladysAssistant/Gladys · GitHub
For those who have Gladys Plus, could you test at this
I just tested , it’s all good for me
For me as well 
have a good day
Same, it’s good!
What responsiveness, @pierre-gilles, that can be mentioned in the comments of the future homepage!
It’s merged and will be included in the next Gladys release
Thanks for your tests 
Bug fixed in Gladys Assistant v4.20