BrianGilman, Ken: true and true. The problem is apparently know by Adobe (https://bugs.adobe.com/jira/browse/FP-295), yet it's still unresolved there. BTW: it appears on other systems as well, not just Ubuntu. Also, the issue really does not happen (or is not so perceivable) on Chromium. So I guess this is really a Firefox + Flash problem, which is incidentally what I wrote in the summary & description.
BrianGilman, Ken: true and true. The problem is apparently know by Adobe (https:/ /bugs.adobe. com/jira/ browse/ FP-295), yet it's still unresolved there. BTW: it appears on other systems as well, not just Ubuntu. Also, the issue really does not happen (or is not so perceivable) on Chromium. So I guess this is really a Firefox + Flash problem, which is incidentally what I wrote in the summary & description.