void remove(ComponentPlaceholder placeholder) {
		if (getTopLevelNode() == null) {
			return;   // this node has been disconnected.
		}

		if (placeholder.isActive()) {
			if (top == placeholder) {
				top = null;
			}
			invalidate();
		}

		WindowNode topLevelNode = getTopLevelNode();
		topLevelNode.componentRemoved(placeholder);
		doRemove(placeholder);
	}
Removes the component from this node, but not from the manager. Used when
the component is moved.  If component is active, it will remain active.
@param placeholder the object containing the component to be removed.
Ghidra/Framework/Docking/src/main/java/docking/ComponentNode.java