Set the preferred width and height of the control.
import org.eclipse.swt.SWT; import org.eclipse.swt.layout.FormData; import org.eclipse.swt.layout.FormLayout; import org.eclipse.swt.widgets.Button; import org.eclipse.swt.widgets.Display; import org.eclipse.swt.widgets.Shell; public class FormLayoutFormDataWidthHeight { public static void main(String[] args) { Display display = new Display(); final Shell shell = new Shell(display); shell.setLayout(new FormLayout()); FormData formData = new FormData(); formData.width = 100; formData.height = 200; Button button1 = new Button(shell, SWT.PUSH); button1.setText("button1"); button1.setLayoutData(formData); shell.setSize(450, 400); shell.open(); while (!shell.isDisposed()) { if (!display.readAndDispatch()) { display.sleep(); } } display.dispose(); } }