The last row is not fully visible when the gridview is scrolled to the bottom in case RowHeight is set to less than 20px. The less the row height the smaller the part of the last row which is visible. This is reproducible only in Office2013 theme. 

Scrollbar scrolls unexpectedly when column width is changed. Check the following video for a reference:
http://screencast.com/t/Y6IwtREc