Closing a canvas does not work properly if more than one canvas is open.

[danlipsa]

The following script opens 4 canvases, plots the same fillarea and closes the canvases one at a time. The canvases get cleared but not closed. This does not work on Linux but works on Mac.

import vcs
import sys
import vtk

f=vcs.createfillarea()
f.x=[.2,.5,.8]
f.y=[.2,.8,.2]
f.color=["red"]

x=vcs.init()
x.plot(f)

y=vcs.init()
y.plot(f)

z=vcs.init()
z.plot(f)

w=vcs.init()
w.plot(f)


x.interact()
x.close()

y.interact()
y.close()

z.interact()
z.close()

w.interact()
w.close()

If we replace .interact() with .backend.interact() everything works fine.