observe: Region::setInactive/setActive not working

[RaiMan]

The test case:

• img.png is either visible or not
• using observeInBackground() with onAppear() and onVanish()
• want to use Region.setInactive() and Region.setActive() to manage when what event should be observed

The problem: activation/deactivation of events did not work.

It is fixed now and additionally we have Event::setInactive() for use in a handler.

In the following workflow the image is not visible in the beginning and then appears and vanishes again and so on.

start = time.time()
def now():
  return 0.01 * int(100 * (time.time() - start))

def handler(evt):
  global stop
  cnt = evt.getCount()
  if evt.isAppear(): 
    name = "ona"
    evt.setInactive()  # deactivate onAppear
    evt.getRegion().setActive(onv)  # activate onVanish
  else : 
    name = "onv"
    evt.setInactive()  # deactivate onVanish    
    evt.getRegion().setActive(ona)  # deactivate onAppear
  print "in handler:", name, cnt, now() # activate onAppear
  if cnt > 2: stop = True
  
img = "img.png"
ona = onAppear(img, handler)
print "ona:", ona
onv = onVanish(img, handler)
print "onv:", onv
setInactive(onv) # to avoid triggering onVanish at start
stop = False
observeInBackground(FOREVER)

while not stop:  
  wait(1)

While the script is running I am making the image hidden/visible manually.
... and the printout:

ona: 1576919468469
onv: 1576919468495
in handler: ona 1 2.68
in handler: onv 1 5.15
in handler: ona 2 7.58
in handler: onv 2 9.87
in handler: ona 3 11.7