turning white areas transparent

[handrawn]

I think I know what you mean.
I have a one-click filter effect, originally for photoshop, but it works with my painter ix5 so maybe with your version too.
Attached is screen shot of the layer before after and with fills.
Canvas has been hidden.
Is this what you need? - if so I'll dig a copy out for you, its free and in the public domain.
Works with xara too.