Table > Width setting: how to set None?

Table > Width setting: how to set None?

Zoho wiki's table formatting features and its UI are generally very impressive and useful.

But one issue consistently bugs me. In the Table Properties UI, how do you set the table width to automatic? That is, have it omit the specification of 'width: something' ? 

I can edit the html to remove that spec from the style="..." attribute, which achieves the desired automatic width effect. And that shows up as a blank in Table Properties > Layout > Width.

But if I edit a new table to try to change the Table Properties >  Width setting from 100 to blank, the dialog doesn't register that change.

Suggestions?  Thanks, Graham