Activate FE-/Macro Structure: Switch between processing of FE respectively Macro model

Macro model and FE model can be loaded in memory simultaneously, but only one kind of structure is active for processing. The title bar of the graphics window shows, which structure is active. The command switches processing to the inactive structure. The label of the menu button shows, which kind of structure will be set active by clicking the button.

Hint: If memory is barely, only one kind of structure should be loaded at a time.