This happens in part editor.

Hovering over something highlights *but does not select it*. >If you use the arrows with items only highlighted then the canvas - and everything on it - moves. >If you use the arrows with items only selected then theselected items move and the canvas does not. To select things, please review these sections the tutorial: <https://easyeda.com/Doc/Tutorial/introduction.htm#1.Leftclicking> and; <https://easyeda.com/Doc/Tutorial/introduction.htm#4.Selectmoreshapes>

Yes, Bug under Firefox, like https://easyeda.com/bbs_view_2073.htm