Stacking never starts if there is no space for the first part

[echer80111]

Stacking got through the first loading bar, but then froze up before placing the first piece (which I think would be the core of this puzzle).

Clicking Stop produced the appropriate confirmation dialog box, but after confirming that I wanted to abort, the program froze completely.

I believe this happened because the bounding box settings hadn't been updated from the defaults, which made it so that the first part was impossible to place in a box with the "Initial Z"

There are a few things that probably need to be fixed here:

1. Something is going wrong with the algorithm that grows the bounding box, because the largest piece in this stacking is a sphere with a diameter of 52mm, and the maximum Z was set to 90mm. It should have been possible to fit that piece by growing the box. Not sure why it is hanging instead.
2. The bounding box settings should not be hidden away on a separate tab. See the UI suggestions in other issues.
3. The bounding box settings should automatically update to a suggested size like it did in TomZ's original PartStacker.
4. Clicking Stop shouldn't freeze the program!