The closing of the dropdown invokes a chrome workaround for forced redraw of the chart. I just hoped that it might magically work for this issue as well.
I will see if we can reproduce the issue on an emulator. If not, then it will take a bit longer while we track down the exact phone model you have.
Perhaps it would be possible for you to send us the application that exhibits the problem? That way we should be able to do the repro quicker.