P: Incorrect cropping of "Define Pattern" in 32-bit mode in some cases.

Incorrect cropping of "Define Pattern" in 32-bit mode in some cases.

Reproduce steps:

- Create a new 32-bit image with size 32x32px.
- Fill it white.
- Select the right-most pixel column (x = 31, y = 0..31) and the botto-most row (y = 31, x = 0..31) and fill them black.
- Select everything (32x32) with the selection tools.
- Edit > Define Pattern:

Expected: I see a 32x32 pattern in the preview.

Actual: I see a cropped 1x32px pattern which isn't what I selected.