Apply execution functions add commands to the command buffer, then immediately flushes it, and triggers the contents of the display to be updated when applicable.
For example, screen_flush_context() is of type apply execution. This API function adds the flush command to the batch-processing command queue. Then the function proceeds to flush this queue, and in doing so, communicates with the Composition Manager. The contents of the display will also be updated.
The return value from apply execution functions indicates whether or not all commands flushed from the batch-processing queue have been executed successfully. A successful return value indicates that all queued commands were processed and executed without errors. An unsuccessful return value indicates an error in either the execution of a previously queued command, or the flushing command (the command from the call of the apply execution function).