find
Finds a #GHook in a #GHookList using the given function to test for a match.
Return
the found #GHook or null if no matching #GHook is found
Parameters
hookList
a #GHookList
needValids
true if #GHook elements which have been destroyed should be skipped
func
the function to call for each #GHook, which should return true when the #GHook has been found