You can do quite a bit of conditional nested logic now, assuming the attributes you want are available via properties, functions, or local variables by using Boolean operators in an expression in the condition builder and equating it to true.
For example, if you wanted to say…
(If text of foo is “x” OR text of foo is “y”) AND (text of sum is greater than 0 OR selected of check equals true)
…choose “value” in the leftmost dropdown in the condition builder, hit the fx button for the value, and fill it out like so:
Then just make sure you are equating this expression to the value true:
This is one of the reasons I want all attributes of everything (e.g., states of dynamic panels, visibility of objects…) available in the fx panel!