RoaringApps lets people know with which versions of OS X/macOS their apps (that have been reported on) are compatible, but I thought they'd get feedback from more than just a handful of users.
No, DW CS3 is NOT working OK in High Sierra, possibly because of the problem you've run into.
I can't answer your last question without your telling me when DW CS3 was released.
More: You also need to check the Parallels documentation to see with which OS versions it's compatible.
Edited by artie505 (05/08/19 10:25 AM)
Edit Reason: More
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