FYI, Several months ago I reported a problem with the Raspbian desktop task bar in the thread below:
I have since upgraded to Raspbian "Stretch", and the problem seems to have vanished. I am still using the same version of Xojo (2017r1.1) so that eliminates Xojo as a suspect.
If you are developing full-screen, touch-screen applications, this is probably good news. Just thought you might like to know.