Magic Lens not working when spacing > 1

[codeling]

When spacing of dataset is > 1, the magic lens only shows the original dataset in the slicers, never the additional modalities (despite showing their label).

[Nepelius]

When setting spacing to 1 for two samples and using the magic lense, "Slice YZ" 2D view does not work with magic lense. The other two perspectives "Slice XZ" and "Slice XY" are working as expected. The area inside the magic lense rectangle stays unchanged for "Slice YZ" like shown in the screenshot.

[codeling]

It seems 1 is not the exact threshold. I have not determined yet what the exact conditions are under which the bug appears.

The workaround is to disable the magic lens; then change the spacing via the dataset settings (pencil icon on a dataset), to be safe, set it to a value < 1; then re-enable the magic lens.

[codeling]

This problem also seems to have to do with the dataset size somehow; for a size of ~ 700^3, the issue happens for a spacing ~>= 20; for a dataset of size 100^3, it happens only for a spacing ~>= 150.