exchangeRate := 1.33.

(window := MacWindowFrame new)
  text: 'Currency Converter';
  position: 20@60;
  extent: 300@160.

(amountLabel := MacTextLabel new)
  text: 'Amount to convert:';
  extent: 100@15.

(amountField := MacTextField new)
  extent: 100@15.

(resultLabel := MacTextLabel new)
  text: 'Result:';
  extent: 100@15.

(resultField := MacTextField new)
  disable;
  extent: 100@15.

(convertButton := MacPushButton new)
  text: 'Convert';
  beDefault;
  extent: 100@20;
  when: #clicked evaluate: [
    resultField text: (
      amountField text asNumber * exchangeRate
    ) asString].

window
  layout: LinearLayout new beVertical;
  addControl: amountLabel;
  addControl: amountField;
  addControl: resultLabel;
  addControl: resultField;
  addControl: convertButton layoutConstraints: (
    LinearLayoutConstraints new
      anchorRight;
      stretchHorizontally: false;
      yourself).

window open