So this just gets weirder and weirder. Now that I've gotten a much shorter double click that does not bother me significantly in use, but the mouse scrolling behavior is just weird, and I offer it in case it rings a bell for anyone. Here's what I've done.
As mentioned above, I tried one of the world's simplest mice, a Microsoft that I don't use because I don't like the feel. It worked fine.
And as my mouse was very old and a bit sticky, I bought a new mouse, a wireless Microsoft Wireless Mobile 4000. Brand new. Hooked it up and.... it's scrolling the film strip on the preview backwards.
Except... after a lot of experimentation, here's what I see.
First, to reiterate -- I've tried this now on a ton of other programs from browsers of the web to browsers of photos, lightroom and photoshop, etc. It works exactly as expected on every other program.
In Photo Mechanic, on the Contact Sheet, it works directionally correct, but requires a certain threshold of speed to move at all. If I scroll bump by bump it does nothing.
In the film strip if HOVERING OVER the film strip, it works directionally correct as well, and just like the contact sheet, it requires a certain speed before it does anything at all. But when it works, it is in the right direction.
If, however, you are over the preview image itself, it does NOT require any specific speed, it scrolls as slowly as you want to turn the wheel. And if you turn it slowly, it goes forward even when you scroll the wheel backwards. As you scroll faster and faster backward, it starts to mix in a few backward (correct) with all the forward movement -- kind of a stutter. It's like the same threshold for any movement while hovering over the filmstrip or contact sheet is also a threshold for going in the right direction (but still mixed in with lots of wrong direction).
Hovering over the large image in the preview is where I initially tested it, and that's why I saw it going backwards all the time, as I was going slowly to make sure I could tell direction by the actual images. It is very speed sensitive to getting the direction right.
It seems clear Photo Mechanic is doing something a bit differently in accessing the mouse information from your typical program. Whether this is uncovering some subtle problem in my setup, or some limitation of Microsoft's implementation of their more advanced interfaces I do not know (the non-working mice have more buttons and are controlled by the Microsoft Keyboard and Mouse software, the other that worked is just a HID compliant mouse), or they are not implementing some aspect correctly that only shows up in certain cases... ?
I'm generally using auto-advance or the arrows to navigate anyway, so this is a non-issue for me, especially now that I see it is related to where I hover as well.
But it is just weird. If someone with a similar setup (4+ button microsoft mouse on Windows 10 x 64 with their mouse software) is curious, give it a try. Or if someone sees it scrolling backwards, maybe they will find this note.
