I decided to post this list publicly, so others can contribute to it. Feel free to post any problems you find in IE that don't occur in other browsers. I don't know of any open issues for IE9 or IE12, but the issues of other versions are very minor.
The following issues have been fixed, but will still affect dragonbasher.com until it is updated: (A patch was going to be applied somewhere between Thanksgiving and Christmas to fix these and improve other things, but it was stopped by the weather, actually. :p)
1. The onresize workaround for IE 9 and earlier was left out, causing the chat window to look broken in those versions. (It still worked, except for bug #1a.)
1a. The chat input line thought it was full when it wasn't, keeping some players from sending chat.
2. IE uses a context z-index model, while other browsers use a global model. When certain things overlap, the one with the higher z-index is shown in front, but IE may show a lower z-index in front due to a variety of factors called the context. Because of this, I had to remove some reliance on z-indexes.
2a. IE was often (100% chance until the map scrolls, then about 50% chance) chopping heads off of players when they were standing on one row of tiles (around the middle of the view area.)
2b. Buildings and large enemies could also be cut in half, or even quartered, when either on the same row of tiles mentioned in #2a above (with the same chance of occurrence) or in two columns in the middle of the view area (with a 50% chance of happening.) This has a fix, currently, but we may like to find something better. (Buildings are currently invisible on dragonbasher.com, and I don't know of any enemies there, yet, so this one is fairly moot.)
3. The pointerEvents workarounds were causing some mouse clicks to be ignored. (I was interrupted during an edit session and forgot where I had left off. :S)
3a. jQuery errors were being reported for this problem, but they actually had nothing to do with jQuery.
The following issues are still open:
4. IE8 still doesn't display resizing cursors over the edges of the chat window and sometimes shows a wrong cursor over the scrollbar. I'm not sure that's really enough of a problem to further code for the old browser, though. (I might still try things if I have time. Feel free to give suggestions.)
-QuaCzar : SysOp | Anarchy Leader | #1 Magic