window = new SketchFrame("画图", this); // Create the app window
Toolkit theKit = window.getToolkit(); // Get the window toolkit
Dimension wndSize = theKit.getScreenSize(); // Get screen size
window.getContentPane().setBackground(Color.black);
// Set the position to screen center & size to 2/3 screen size
window.setBounds(wndSize.width/6, wndSize.height/6, // Position
2*wndSize.width/3, 2*wndSize.height/3); // Size