Javascript-only onmouseover things normally feel wrong, but throw in the css needed to change the cursor to a pointer (or a hand for dragging) and suddenly it feels like the web again.

Java and CSS give you a bunch of proper pointers by default, but Flash only gives you two before you have to hide the cursor and fake it at the framerate of the Flash player instead of the OS. Always hated that.

I think every non-native GUI toolkit has its smells – do the widgets respond to all the OS’s usual keyboard shortcuts (particularly for navigating around text). Adobe products work one way, Microsoft another – I use the kinds of interactions you’ve identified to sniff out a new app and see which pathways will work and which won’t.