def get_backdrop_size(nodes_sel):
	"""get the XYWH of backdrop nodes based on given nodes
	@nodes_sel: (list of obj) list of selected Nodes
	return: (list of int) [bdX, bdY, bdW, bdH]
	"""

	# Calculate bounds for the backdrop node.
	bdX = min([node.xpos() for node in nodes_sel])
	bdY = min([node.ypos() for node in nodes_sel])
	bdW = max([node.xpos() + node.screenWidth() for node in nodes_sel]) - bdX
	bdH = max([node.ypos() + node.screenHeight() for node in nodes_sel]) - bdY
	
	return [bdX, bdY, bdW, bdH]