[Jeff]

Use the Panel.getBoundingBox method to get the panel dimensions:

import viz
import vizshape
import vizdlg

viz.go()

myPanel = vizdlg.Panel(align=viz.ALIGN_LEFT_BOTTOM)
row = vizdlg.Panel(layout=vizdlg.LAYOUT_HORZ_BOTTOM,border=False,background=False,margin=0)
row.addItem(viz.addText('Textbox'))
textbox = row.addItem(viz.addTextbox())
myPanel.addItem(row)

circle = vizshape.addCircle(parent=viz.ORTHO,scale=[20,20,1],color=viz.RED)

def showPanelDimensions():
	box = myPanel.getBoundingBox()
	width = box.width
	height = box.height
	print width,height
	circle.setPosition([width,height,0])

myPanel.setPanelScale(2)
showPanelDimensions()