Full Screen

I usually use CalGraph with a split screen. The left side of the window shows the buttons like a calculator, the right side shows the graph.
You might want the graph to be bigger. You can click  in the upper right corner of the window so the window fills your whole monitor screen.
Maybe that still isn't big enough. Click Customize and then Restore Full Screen. Now your screen is either just the calculator buttons or just the graph. If you have just the graph and you want the buttons, click the green button Back to the Calculator. If you have the buttons and you want the graph, click on draw/cal.
If you decide to look at both at once, click Customize and then Split Screen.
The two parts of the split screen need not be the same size. Put the mouse over the split line and drag the split to the left or right.