In the same place where the property sheet is located you can find the screen window:
The screen window is useful to find graphical objects that placed on the screen behind other graphical objects and to find and edit properties of the object inside the group object:
By clicking right button on the screen object you can call context menu:
List of menu items with their functions:
▪Delete object - delete selected graphical object from the project.
▪Object properties - call object properties window for selected object.
▪Add to Library - add selected object to the library (preliminary you have to create user-defined library in Add graphical object window).