Hello, the client will display as such if the screen size or resolution is not able to display the entire game, if possible, I would suggest trying to alter you monitors display resolution to see if it helps.
May I ask what screen resolution and size you are having issues with? The client currently does not have an option for adjusting the resolution it is displayed in.
What browser are you trying to use? Many browsers do not allow the use of flash anymore, Maxthon5 is one browser that does allow the use of Flash. The miniclient does not currently have an option to set full screen.