RenderListBox::listIndexAtOffset() does not take top padding and border. To see the problem, open the URL and try to select items.
Created attachment 12608 [details] [WIP] Patch w/o change log and test
Created attachment 12609 [details] Another test case This test case lets you play with autoscroll and with clicking below the last item.
Comment on attachment 12608 [details] [WIP] Patch w/o change log and test >+ return newOffset < numItems() ? newOffset : - 1; Space between unary minus and one.
Created attachment 12615 [details] Patch, including test and change log
Comment on attachment 12615 [details] Patch, including test and change log Oh, my bad! Mitz told me about this and asked me to fix it in my patch! This patch is full of maximum goodness. r=me
Landed in r19037.