WIMP
  All Wimp programs have two features in common - they have to initialise
   themselves with the Task Manager and they have to use a poll loop.
   They are both _swi accessed, so will have values in and out.
    SWI Wimp_Initialise
      On entry
        r0 Last wimp version * 100
        r1 0x4B534154 ("TASK")
        r2 Task description
        r3 Messages list required
        On exit
        r0 Current wimp version*100
        r1 Task handle
  The wimp version relates to the RISC OS version. This is normally 310
  (corresponding to OS 3.10), through 350, 360, 370 and 400 are all used.
  200 (OS 2.00) is unlikely to be seen now.
  r1 is actually just a fudge to filter out all the old pre-RISC OS
  programs which aren't likely to pass this on initialisation!
  The task handle is the name by which the task manager knows what the
  application is. Every application, be it WIMP or CLA will have had
  one of these assigned to it on start up.
  The poll loop is the manner by which the program itself keeps
  up-to-date with what events have been received.

© JR 2013