Intermittent flicker with visual effect dissolve

[nower]

I am displaying text on a card that can be changed by pressing a button, and I use the "dissolve" effect when the text is changed.
I lock the screen for visual effect at the beginning of the handler that changes the text, then update the field on the card, and then unlock it with the visual effect.

Quite often this works well. But intermittently there is a flicker happening during the visual effect that is rather unpleasant.
It does not depend on the content, because sometimes it occurs when going back and forth between the same texts, and sometimes it doesn't.
It is irregular, sometimes it occurs at every second or third text change, sometimes it doesn't occur for 10 text changes.
It does't occur if I don't use QuickTime visual effects, but then the dissolve looks very ugly.

Any idea why that might happen and what I can do to resolve it?

Thanks!

[Dixie]

Hi...

Starting with 'John' in fld 1...

Code: Select all

 on mouseUp
   lock screen for visual effect
   put "Peter" into fld 1
   
   go to this card
   unlock screen with dissolve
end mouseUp

This works fine for me... no flicker !

[nower]

It works fine for me 90% of the time, too.
But then randomly there is a flicker.
As I said, the transition between the same texts may work fine one time and then have a flicker the next time.
Between the lock screen and unlock screen I set border color, an imageSource, and enable or disable several buttons and menus.
But even if I comment all of that out, the flicker still occurs randomly.

[nower]

It seems to be platform or machine dependent.
I have the flicker on my Windows 7 machine, but it doesn't happen on a Mac OS X machine.
Strange.