@Dave - I know what you mean. Even apps notionally doing the same thing can differ markedly in the way they are used and in this instance I'd actually argue that it's AutoCAD's way of doing things that is peculiar (I'm not aware of other programs where you have to press Escape to unselect). It is a bit disappointing however to hear that Google don't seem to be interested in at least offering a customisation feature to disable Escape given how large a potential market AutoCAD users represent.

Thanks for the replies If there's anywhere to suggest new features I'll add my name to that one.

Coming from an AutoCAD background it's second nature to press Escape when we want to unselect a group of lines or cancel a command. However, in Sketchup pressing Escape at the wrong time can result in the dialogue / pallette window you're working in closing. I know this isn't the fault of Sketchup's design but it is frustrating. Is there any way of disabling this behaviour?