Highrez

XMBC Version: 2.18
Windows Version: 10
Mouse Information (brand/model): Logitech MX Anywhere 2
Computer Information: some Dell laptop
Did the problem occur after an upgrade of XMBC or Windows?: yes, upgrade 2.17 to 2.18
How long have you used XMBC?: a few years
What language and keyboard layout do you use in Windows?: German QWERTZ

Clear description of the problem:
I have a 5-button mouse and configured MB4 to "Simulated Keys: (repeat)[{PGDN}]" and MB5 to "Simulated Keys: (repeat)[{PGUP}]", which is excellent for scrolling through long documents btw. Auto repeat delay is set to 0 (Windows Default).

Since the update to v2.18, pushing MB4 or MB5 scrolls twice. More precisely, PGUP or PGDN are pressed when I push MB4/MB5 down and when I release it. This was not the case with 2.17, it just sent PGUP/PGDN when I pushed MB4/MB5 down (and repeatedly sent when held pressed down, of course), but not on going up.

Is there a new or alternate setting to return to the old behavior?

Urm, it wasn't an intentional change - but you could try adding {press} before the command.. You may also need this:
"{press]{pgup}{repeat}{pgup}" but I'll have a look and see if I have accidentally changed this behavior.

Same problem here. Have rolled back to 2.17 where the problem does not manifest.

I'm away today but I have a few days off left after the new year break so I will try and have a look tomorrow and see if I can reproduce this and fix it if it is indeed a change that shouldn't be there.

FYI, {PRESS}{PGUP} does not change this behavior (nor does adding {REPEAT}{PGUP}).

OK I can confirm the same behaviour here - not sure why yet, but there is a way around it (for now) and I was wrong with the press/repeat. What I meant was the new {OD}/{OR}/{OU} tags....

This works:
{OD}{PGUP}{OR}{PGUP}
What that says, is on button down, send a PGUP and during a repeat call, send a PGUP but nothing on a button up. Now to figure out if I can restore the previous behavior whilst also allowing these three new tags!