When I installed the mod for beta 1.7.3, I realized that the left mouse drag feature does not work, nor does double clicking an item to bring all the stacks together.

Hey,

double clicking an item to bring all the stacks together

This is not a mouse tweaks feature, it is a vanilla feature

left mouse drag feature

I'm not sure which one you're referring to, but if you mean the one that redistributes items evenly between slots, than that is also a vanilla feature.