[Geoff Bacon]

Hi Mike

That makes sense.
How about closing the PDFs in a self terminating thread(s) i.e. no need to check for completion? Of course, this will probably have minimal effect if the tablet has a single cpu and/or the scheduling is co-operative rather than via interrupts.

Also, using a thread might not make any difference if there is another immediate call to the external PDF library (this might hang until the old PDF has been fully released).
If memory is not an issue (it probably is) and if the library allows it (which it may not), you might be able to open the next PDF file before releasing the old PDF file via a self terminating thread. This should provide quick song changes without hanging the GUI (assuming the cpu has enough oomph and the PDF libraries are well written). The only way to tell would be to code it and I can see that testing will be difficult as the problem is intermittent.

I think that it about all I can contribute to this problem.

Many thanks for all your work developing/maintaining MSP

Geoff