MOSSYS: is totally wrong.
Such an Assign is normally not needed.
Better install such prg by hand.
Put additional MUI classes to SYS:Classes/mui

Well, a little difficult but better dont
assign it at all. Install the applications
by hand.

ok, thx to both.

My MUI: points to MorphOS:morphos/MUI/ .. haven't had problems.

my understanding is that MOS mui files are all installed in the MOSSYS:classes/mui/ directory.
and that any 68k mui files that are needed by "classic" amiga programs are placed in the sys:classes or sys:mui directory as needed by the specific program.

as i'm still new to this thing, don't go only by what I say.

but I was able to get ImageFX and ZoneXplorer to work properly by paying attention to these issues.

On the occations that I needed it, I just made a new temporary directory in ram. i.e., ram:mui/, ram:mui/libs/, etc. Then I made an assign of mui: to ram:mui. The secret to this is to check those libs before putting them into SYS:Classes/MUI/, then to remove that assign.