When in slide show mode, the menu bar and that "x" are not visible.
Answer:

Explanation:
We'll be using u-substitution for this problem.
Let

Substitute

Split the fraction

Move the constants out

Simplify

Integrate

Substitute

The answer is a Scroll bar, the description fits perfectly because you need to move it to see more of the content you are viewing, and it wont be completely. when the item does appear completely on screen then the bar is relatively large and there is no need for scrolling, however the opposite occurs during when you cannot see all of it.