Nested lists not properly themed

Nested lists not properly themed

I use the latest js and CSS published on this site and I ran into a problem since one of the last releases, probably when upgraded from 1.2.x to 1.3.x. I did not bother do revert it.

When I define a data-theme="a" in listview ul then the header in the submenus are not formatted!
Investigation in the code as used after rendering I found these extra pages on the bottom of the html as generated by jQuery-Mobile. Although the original <li> is formatted with data-theme="a" these extra pages with submenus are in data-theme="b". As I did not incorporate data-theme="b" into my CSS it ended up in an unformatted header of the submenu.
As one  can only influence this behaviour other than with some jQuery code I took the easier route and added a copy of theme A for theme B and problem solved for the time being. It is a workaround but this behaviour should be investigated and altered.  For instance the use of the data-theme as used in the original listitem could be copied. Setting of the data-theme for submenus is a more elegant method, but I could not find any method for that in the documentation.
Just have a look at this site  http://www.nederlandse-danssport.org/Mobiel/index.asp to check what I am trying to tell.