Well, I tried this in IE11 on Windows 7 x64, all three buttons works. IE11 still works.
screenshot: http://ww4.sinaimg.cn/large/798f7769gw1eceuea9cwhj211i0ox10b...
screenshot: http://ww4.sinaimg.cn/large/798f7769gw1eceuea9cwhj211i0ox10b...
http://ww3.sinaimg.cn/large/798f7769gw1eceugu2bhlj21130r4qa4...
BTW, what are the plugins you've installed in IE? What's the OS version? Performing more information will help everyone to find the bug.
I reset all IE settings to default, as well.
I am running in a VirtualBox virtual machine, though I've reproduced this on non-virtual machines, as well.
What else is useful?
Two of my friends tried on Windows 8.1 Pro x64, still no crush.
One commonality seemed to be Windows 7 Home Premium SP1, but I see someone else was using Windows 8 and reproduced it. Hmm…