New feature: Thick slab reconstruction from slice controllers and views

Hi, very useful tool! Thanks.
However, the slab thickness seems to not work correctly on my data. As you can see in the capture below, the two red lines already cover the whole volume, but the MIP image in the Red view does not really show all vessels. If I increase the interval between the two red lines, more vessels will appear on the MIP image. Do you know why? And how to fix it?