Qt/E 4.8.4 WebKit apps hanging, icon thread blocked

[davem]

We're using Qt/E 4.8 WebKit demo browsers on an embedded ARM device, one based on Qt SDK example browser, another based on QML WebKit example.

We've been seeing occasions when browser just locks up, and originally thought it was due to our touchscreen driver. However one of our developers found that touch events are still being received by the app's input handler. We've seen this now on 4.8.3 and 4.8.4 runtime versions.

Attaching gdb recently showed that an icon manager thread was blocked waiting on a condition to be signalled, and that other waiting WebKit threads might not be able to trigger the condition.

Has anyone else seen this sort of hanging with Qt/E WebKit?