set_locked_state

Locks the state of an element, so state changes of the parent don't affect this element anymore.

Note that this is racy if the state lock of the parent bin is not taken. The parent bin might've just checked the flag in another thread and as the next step proceed to change the child element's state.

MT safe.

Parameters:

this	a Element
locked_state	true to lock the element's state

Returns:

true if the state was changed, false if bad parameters were given or the elements state-locking needed no change.