Stupid bugs I saw today:
Safari: After properly handling one page-down scroll event, it got into a mode where it ignores the scrollbar. I could not scroll the webpage up or down by mouse click or mouse drag.
Word: double-click a word to select it, control-click to bring up a menu, select "New Comment", and start typing a comment. The first couple of letters end up after the selected word instead of in the comment field.
Apple and Microsoft should be embarrassed that bugs this basic are happening now.