Scroll requests from mouse wheel

RISC OS 5 without !HID running will send vertical Scroll Request messages (Wimp poll code 10) to a window if the mouse scroll wheel is moved. It appears to send five for every step of the scroll wheel.

On our Iyonix, which is still on RISC OS 5.16, the Scroll Request events are sent to any window where scroll requests are enabled in the window definition, even if the window has no vertical scroll bar.

On the Beagleboard running RISC OS 5.22, and the ARMX6 (on 5.23 11-Oct-15) the Scroll Request events from the mouse scroll wheel are only sent to windows which have vertical scroll bars.

How are you supposed to detect the scroll wheel on windows without scroll bars? Such windows might have the need of doing other things when the user rotates the wheel. For example, over the main window in RiscOSM, which fortunately does have a vertical scroll bar, we make the scroll wheel zoom in or out to a different scale of map, unless the mouse is over the scrollbar of course. But it seems that on the latest RISC OS, this kind of effect is not possible unless you have a vertical scroll bar which would not be appropriate for every window.

Is there another way of reading scroll wheel events? I am aware of the RISC OS Select extensions, which I think we also support, but I don’t think they have come to RISC OS 5 yet.

Just bumping this up again in case anyone knows the answer.

I don’t know the answer, but while we’re on the topic of scroll wheels: I’ve found that spinning the wheel when the screen saver is running will scroll the active window (where it’s visible, eg. with “Rain”) but won’t cancel the screen saver!