From Robert's input #8 in DM-8409
There doesn't seem to be a way to show coordinates allowing for XY0 (#8)

The LSST Image classes (Image, MaskedImage, Exposure) support the concept that the bottom-left-pixel is at (x0, y0) not (0, 0). The ds9 display has a way to support this, and it would be good if firefly does too. An example is the patches within a tract (the source centroids are relative to the tract's origin, not the patch); another example is cutouts from e.g. the deblender or the PSF estimation. The ds9 solution is a hack (add another WCS and display both (ra, dec) and (x, y)), but the functionality is very useful.