Tooltips appear off screen

If something in the UI has a tooltip and is near the edge of the screen, the tooltip can appear partly off the screen. The tooltip should be shifted over and displayed fully on the screen.

Also, tooltips should appear ~10 pixels above the cursor, not right over it, as they currently obscure the UI widget the cursor is hovering over when they appear, necessitating moving the cursor to remove the tooltip in order to see what is being clicked.