When I open a schematic on my Android smartphone and touch anywhere on empty space inside the sheet border, the border is selected and drags around.
Touching any object inside the border correctly selects that object and not the border.
Touching outside the border selects nothing.
            
                        
            
                                    
              
                Chrome
                  88.0.4324.152
                AndroidOS
                  10
                                EasyEDA
                  6.2.0