I don’t remember running into this with PG2.X but on PG3, one can get confused with the little blue tab that displays the trash can and other options for the selected element. When creating a new page and adding elements, these tabs are not numbered or color identified so it’s pretty easy to delete something that you may not want to delete. When starting a new page there is a default blank page that is setup allowing you to drag UI elements onto that page. If you place a hero image on the page the property tab will display close to the bottom of the screen and there is also the tab for the blank page located just below it. If you choose to remove the hero and select the wrong tab you will not be able to edit the page without reloading a new one. None of the UI elements will drag and drop.
A suggestion would be to make the main page property tab a different color than the blue (red?) and also number or color the tabs so you can associate them with the elements. The bounding boxes could match the color of the tab instead of being green. I know that there is a tag line in dark gray at the bottom when you highlight elements identifying them but its not productive to have to glance at the bottom of the screen every time you select an element to modify to check if you selected correctly.
I hope this makes sense. I’ve run into the issue of deleting the main tab several times and its pretty frustrating to have to reload and start over.