MorphOS png.datatype expands indexed transparent PNGs to ARGB. When this happens bmh_Depth is 32 and bmh_Masking is mskHasAlpha. PDTA_AlphaChannel is also set to true.
IBrowse code doesn't expect this I think.
Thanks - that would explain it. And presumably, the MorphOS ilbm.datatype doesn't expand to ARGB and sets mskHasTransparentColor instead?
You're right, the full alpha handling is disabled in 68K IBrowse, seeing as OS3 doesn't support it. However, I'll see if we can get away with enabling it somehow, so alpha handling works when running on MorphOS.