function fnRemoveAllBlockLayers() {
		BlockLayerUtils.unblock(this._oBlockState);
		BlockLayerUtils.unblock(this._oBusyBlockState);

		delete this._oBlockState;
		delete this._oBusyBlockState;
	}
Cleanup all block-layers.
Doesn't matter if it's a busy- or regular block-layer.
Used to remove all unnecessary DOM elements and event-handlers during destroy and before rerendering.