created drag handler file
implemented basic dragging manager
fixed order of initialization
refactored drag handler a little more nicely
commented debug output
call start and end handlers
be more careful about dragging state and callbacks
define a callback typedef; declared more event callback functions
auto track a set of elements
renamed callbacks
store a list of elements that the handler monitors for drags
added drag over and out to event monitors
added a comment about callback safety
added todo note
call start handler when drag starts
add enable flag to drag handler
delay disables during drag; pass mouse event on up
if a drag handler is disabled while dragging, wait until it finishes before disabling
pass the mouse event to the end handler if we end by the auto up handler
send over and out events for all targets during a drag
support addition and removal of elements
add and remove down handlers with targets
fixed removal of over events
support a conditions callback to tell if drag should start
pass the handler object and element to the condition callback