The wheel stops nicely at first, but afterwards jumps into the next value, while I haven't released my finger from the wheel at any time. Still the wheel jumps from the initially highlighted and stopped value onwards to the next one.

So mainly, when stopping spinner scrolling, value is highlighted under the finger, when it should only stop the wheel.

Allow for up/down arrows to step up/down the time element with the keyboard cursor. For example, if I have my keyboard cursor on the hours of a time, then pressing up would increase the hour by 1.

Keyboard support for the dropdown... Space to open, tab and/or arrows to cycle through and change the date/time.