I am having this same issue with my new Mac. Late 2010 MacBook Pro with Geforce GT330M 512mb video card.

Unable to fully access the features of the Entity Info box when any line based element is chosen. One can "tab" to the part of the window one cannot see to change a value (such as the number of segments of a circle) and modify the value there and have it take effect.

One can use the size handle feature to increase the window width but cannot increase the vertical size to be able to view the rest of the window.

I have restarted SU. Restarted the computer. Reinstalled SketchUp. Reinstalled the Mac OS using the combo update. To no avail. My old Mac Powerbook has none of these issues, despite having a paltry 128mb of video ram.

I have submitted a bug report, if anyone else is having this issue please send one in as well. I suspect it is a function of the video card in these particular computers relative to the way this window routine is written.

I have also noticed issues with the way the other windows expand under the other panes versus flowing them downward as a group and errors in them staying docked/stuck together.

Thanks

Version 3 is still pretty good - v4 has to be paid for [though not that much $], but then it does have some advantages and a nice web-dialog interface etc - I suggest that you try v3 first to understand what it does and then think if v4 has advantages you need/want...
The 'Smustard' site has some more info on v4... 😉