I have followed the guide here by Volodymyr Vygovskyi, everything is working well, apart from when you filter by a sku, it causes the issue:
> Strict Notice: call_user_func() expects parameter 1 to be a valid callback, non-static method
> Atwix_ExtendedGrid_Model_Observer::filterSkus() should not be called
> statically in
> on line 468
Investigating this I can see that he has the following as his filter_condition_callback:
Is being called statically, I have attempted to correct this by changing it to $this but it causes filterSkus to not be found. Moving the the filter function to helper solves this bit, but then the filter part breaks.
I was hoping someone could kindly help myself solve this.