How do I increase the resolution of BlueStacks?
To change the Resolution of BlueStack:


Open ‘regedit': Start->Run->regedit
Navigate to: 'HKEY_LOCAL_MACHINE/SOFTWARE/BlueStacks/Guests/Android/FrameBuffer/0/’
Double click the value ‘GuestHeight’
Change Base to Decimal
Input your desired Height resolution 
Double click the value ‘GuestWidth’
Change Base to Decimal
Input your desired Height resolution 
Restart your PC, Open BlueStack [It will open up with New Resolution.]  


Check this Link to work Around : 

http://www.techcrises.com/how-to/how-to-change-bluestacks-resolution-in-windows-fixed/