I have enlarged my SL-Window, now I can't refit the size, neither with the green button ...

[valerie Inshan]

Go to your preferences: Graphics tab > check "run Second Life in a window" > window size. Then apply > OK.

You can even do that from the starting screen without having to log in.

[valerie Inshan]

Go to your preferences: Graphics tab > check "run Second Life in a window" > window size. Then apply > OK.

You can even do that from the starting screen without having to log in.

[Cinnamon Lohner]

If you are running Viewer 3.2.4 which is the latest version, there is a known bug where the viewer window cannot be made smaller than 1034x 740 (or something close to that).  You need to either rollback to 3.2.1 or use the Beta 3.2.5 where the bug is supposed to be fixed. 

--Cinn