about a stack fill option (as for malloc-fill and free-fill)

Hi,

	Sometimes, valgrind detects error like "Conditional jump or move 
depends" or "Use of uninitialized value" related to a variable in heap. 
When using with gdb (--vgdb-error=1), a newbie (i.e. my students) can 
have difficulties to understand as the value stored is 0 (because there 
was zeros in heap, not because we set 0 to the variable).
	
	Could it be possible to add an option like --heap-up-fill 
--heap-down-fill (like for stack with malloc), that fills heap memory 
with a specified values (when entering a function and leave a function)?

Would it be complicated to implement?

thanks :)
Julien.