If you've never played Power Grid on BSW before, for the first time you enter, all the graphics and support files need to be downloaded from BSW servers to your computer. This happens automatically but can take time, especially if you do not have a broadband internet connection.
When I joined the game, via the "Gameyell" button on the previous screen, this blue window is included on the game screen. You can see my nick/handle in the first player seat. When others want to join this new game they can click on the "JOIN" button in this blue window.
The "invisible" check box, when checked, makes this a private game.
"Drawseat" is useful in many other games hosted on BSW, but I don't believe it has any purpose in Power Grid.
The "map" checkbox, when acivated, allows you to change the map between the USA and Germany. I left the default map for this room alone and kept it at USA. At this time (January 2006) the new Italy and France maps are not supported on BSW.
At the bottom of the window you can see the result of my "gameyell".