I have a very small suggestion for improving the user interface:  as much as possible, the menu arrangements should be consistent.  Where items are shown in different menus, they should be shown in the same order.  When you use a menu over and over, your mind subconsciously starts remembering where items are located, and your eyes automatically go to the correct spot.  This process is interfered with when menus show items in different order.

 

For example, the column pulldown menu is on the left; the column context menu is on the right:

 

 

In the left menu, WYSIWYG is above HTML codes;  on the right, the order is reversed.  "Add/Remove columns" is 2nd in the left menu; 5th on the right.

 

Feel free to think this is ridiculous but it's the way my mind works as a writer.  Using consistent, parallel structure makes it easier for the reader and user.

 

Wayne