ResolutionFirst, please, try to decrease guest resolution by right-clicking the desktop, then "Properties", then "Advanced" tab. For this, install Parallels Tools inside guest menu "VM->Install Parallels Tools" and then, if you wish, add some custom resolution to the VM in its configuration editor or choose some default value. Then change the resolution in guest as described above.
So, you are now able to see full guest window while not in fullscreen.
The second, go to menu "Parallels Desktop"->"Preferences"->"User Interface" tab. Then check "Allow to change guest screen resolution" and uncheck "Allow to change Mac OS X screen resolution" and click "Ok". Now your guest system will run at native Mac OS X resolution while in fullscreen and at your custom resolution, while in windowed mode.
Note: you must install Parallels Tools for this to work.