This post came about as a request from another forum member. We were having a discussion about Mac OS style and I thought this might help your developement efforts on your cross platform solutions:
I have two style sheets in my solutions. One for Mac, and one for everything else.
Then at startup - I have a method that checks the platform, and then uses application.overRideStyle() to use the Mac style sheet on the Mac, and the "regular" stylesheet on every other platform.
Another tips:
1) You want NO LINE around the fields that are combo boxes (on the mac) - but DO want them everywhere else;
2) Button heights less than 26px will not draw in rounded buttons;
3) Field heights should be at LEAST 22px or the popup menu widget won't draw properly;
4) Lucida Grande draws a little wider than Tahoma;
5) If you design for the Mac, then in general, the PC version is fine.
Hope this helps.