Increased right margin on close button

[mhweaver]

In OS X, the scroll bar tends to completely cover the close button.

Screenshot of issue

Shifting it slightly to the left allows the button to still be usable, even when the scroll bar is visible, without it looking weird.

[ErikHumphrey]

For now, before the improvement, one could try turning on "hide scrollbar when not being used." Thus the user would have to wait for the scrollbar to disappear before clicking the X close button.

This should be fixed, though.