@leocg It depends on two things: the number of items in the list and the vertical size of the window. The menu list height is also small have to surpass the window height.
But their is a interesting behavior:
many tabs opened from the same domain;
mouse over one of the tabs and the menu will cover it;
but if you move the cursor to other tab from the same domain, the menu adjust it self for the right height, not covering the tabs bar anymore.