private void btnBrackets1ActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btnBrackets1ActionPerformed
        //Add paranthesis to the current cursor position.
        int oldCaret = txtExpression.getCaretPosition();
        txtExpression.setText(txtExpression.getText().substring(0, oldCaret) + "()" + txtExpression.getText().substring(oldCaret));
        txtExpression.setCaretPosition(oldCaret + 1);
        txtExpression.grabFocus();
    }//GEN-LAST:event_btnBrackets1ActionPerformed