I see the same problem: In the third row, the "modal dialog" has its lower boundary aligned with the lower boundary of the third row. The top (containind the 'x' button) is then hidden behind the red banner at the top.

Guess: They display the "dialog" either with its lower boundary aligned to the row of icons you click, or with its upper boundary aligned to the row of icons you click (depending on which direction gives more vertical space for the dialag), but if the total vertical resolution is too small, part of the dialog may still be hidden.

I see the same problem on my MacBook Air :).