Selection Lock Toggle turns selection locking on and off. Locking the selection prevents you from inadvertently selecting something else in a complex scene.
When your selection is locked, you can click or drag the mouse anywhere in the viewports without losing your selection. When you want to deselect or alter your selection, click Selection Lock Toggle again to unlock the selection.
If you want to select something but cannot, it's frequently because you have locked your selection.
This button is off by default.
To turn on (Selection Lock Toggle), click the button (it highlights). When Selection Lock Toggle is on, you can click anywhere in a viewport and 3ds Max maintains the current selection. This is useful when you want to keep objects selected while you make a different viewport active or when the selection is tiny, or crowded and difficult to select.
To transform an object without touching it:
To avoid accidentally canceling a selection:
To exit sub-object selection mode, do one of the following:
If you've turned off Sub-Object selection and object selection is still not restored, one of the following circumstances might be in effect: