Changing the preferred width of columns to percentages from the Table Properties dialog actually sets them in pixels.

Steps to reproduce:
1) Insert a table

2) select table column property and set preferred width to 20%

3) press "next column" button and set preferred width to 20% 

4) Go to previous columns 

Expected: Column width is set in percentage.

Actual: Some (or all) columns have width set in pixels.