Created attachment 303481 [details]
example showing the race condition

g_main_context_invoke_full contains a race condition. When the context is owned by current thread, but its ownership changes in invocation of the callback function, it will be invoked on the wrong thread.

Suggested solution 1: acquire the context before running the loop and release it after, similar to what is done if the context is thread-default.

Suggested solution 2: keep checking if the context is owned after each callback invocation and the callback returned TRUE. When the context ownership changes, fall through to create idle source.