Apply execution describes API functions where the command from the function call is added to the queue for batch processing, and then this queue is immediately flushed to process all queued commands—previously queued ones included. The display is redrawn if necessary.
Apply execution functions have essentially the same behavior as those of flushing execution, with the exception that apply execution functions cause 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 indiates 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).