[Typo3-dev] Building new backend formelement type

[Tim Kleigrewe]

Hi list

i'm working on an extension where fe_users can sign in for different 
categorys. To make it a bit more easy/complex, i extended the fe_users 
with another kind of group field. That field value should be a single 
integer, to build bitwise conditions in mysql querys and php. (1 & 3 = 
true..., -1 -> all categorys...)
This concept is partly used in the "checkbox" formelement in BE, and i 
think it's a very nice one for groups and permissions, cause its much 
more flexible than saving "1,4,6" values and easier to update than m-m 
connected tables.

Well, actually i need to extend the given typo3 backend formtypes to 
build e.g. a dynamic "checkbox" element, with contents of another table.

A sort of IProc php function (javascript would work either), to check 
different types of formated content in a form field would be great too.
I found passthrough in kickstarter, but this seems only to hide my field.

any ideas or starting tips?

thanks, tim