Test for opaqueness where we create bitmaps in the platform code

amiga/bitmap.c

@@ -328,6 +328,8 @@ struct bitmap *ami_bitmap_from_datatype(char *filename)
 			IDoMethod(dto, PDTM_READPIXELARRAY, bitmap_get_buffer(bm),
 				PBPAFMT_RGBA, bitmap_get_rowstride(bm), 0, 0,
 				bmh->bmh_Width, bmh->bmh_Height);
+				
+			bitmap_set_opaque(bm, bitmap_test_opaque(bm));
 		}
 		DisposeDTObject(dto);
 	}

amiga/dt_picture.c

@@ -159,6 +159,8 @@ static struct bitmap *amiga_dt_picture_cache_convert(struct content *c)
 			bm_buffer, bm_format, bitmap_get_rowstride(bitmap),
 			0, 0, c->width, c->height);
 
+		bitmap_set_opaque(bitmap, bitmap_test_opaque(bitmap));
+	
 		DisposeDTObject(dto);
 	}
 	else return NULL;