In IOS8 Safari there is a new bug with position fixed.
If you focus a textarea that is in a fixed panel, safari will scroll you to the bottom of the page.
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I was able to fix this for select inputs by adding an event listener to the necessary select elements, then scrolling by an offset of one pixel when the select in question gains focus.
This isn't necessarily a good solution, but it's much simpler and more reliable than the other answers I've seen here. The browser seems to re-render/re-calculate the position: fixed; attribute based on the offset supplied in the window.scrollBy() function.
document.querySelector(".someSelect select").on("focus", function() {window.scrollBy(0, 1)});