I think it could be very usefull for a MQX-based application to have a user call-back function available both for the Idle Task and the SysTick timer interrupt.
With a call-back function (hook function), called during each cycle of the Idle Task, the application could execute some lowest-priority processes (it is common to use the idle hook function to place the microcontroller CPU into a power saving mode or just to calculate the CPU time).
In the same way, a SysTick hook function, called from the MQX tick timer interrupt, could provide a convenient place to implement timer functionalities with SysTick resolution.
What do you think about it?