multiple datatriggers & path=Items.Count Value=0

played around with multiple conditions and and or logic, finally what
suited was enabling initially and on each empty field disabling.

tried multiple conditions where for all empty fields disable, thus even
one was not empty enabled the button which was not required! - haha!

looks like a lot can be achieve with datatrigger, multiple conditions
and initial condition! - just a feeling.

multi
* http://miteshsureja.blogspot.in/2011/08/triggers-in-wpf.html

fail experiemnt - multiple condition of not nulls to enable
*
http://stackoverflow.com/questions/356194/datatrigger-where-value-is-not-null

what made me feel i could use Items.Count as Path
*
http://stackoverflow.com/questions/248545/wpf-trigger-for-isselected-in-a-datatemplate-for-listbox-items