How can I make transparency stick?

[Graham Samuel]

First, thanks to Klaus and Ken for the very quick replies to my 
recent question about sounds. Now for another newbie query:

I have some graphics (technically, images) with white backgrounds 
which I want to make transparent. As far as I understand the 
documentation, this should happen if I uncheck the 'Opaque' box in 
the grc's Properties palette. This doesn't seem to work - firstly the 
white bits just stay (solid) white and secondly when I click on the 
object again, the 'Opaque' box is checked again. I can't seem to be 
able to tell the object that I want its properties permanently 
changed - there is of course no 'apply' button, but I guess 'enter' 
or just changing focus should do it. What now? Do I have to convert 
all these types of grc to transparent GIFs - it doesn't seem to be 
what the Transcript Dictionary is suggesting.

Another approach might be to set the object's Ink property, but this 
doesn't seem to appear in the Properties palette at all. An attempt 
to set this via the Message Box doesn't do anything either.

TIA to anyone who can unconfuse me.


Graham
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          Graham Samuel / The Living Fossil Co. / UK & France