Expandable SWT/JFace Dialog

This confounded me for a while, so here's the short:

1. Extend JFace Dialog
2. Keep a handle to the content of your expandable section
3. Do this (from ErrorDialog):

private void toggleDetailsArea() {
Point windowSize = getShell().getSize();
Point oldSize = getShell().computeSize(SWT.DEFAULT, SWT.DEFAULT);
if (listCreated) {
list.dispose();
listCreated = false;
detailsButton.setText(IDialogConstants.SHOW_DETAILS_LABEL);
} else {
list = createDropDownList((Composite) getContents());
detailsButton.setText(IDialogConstants.HIDE_DETAILS_LABEL);
}
Point newSize = getShell().computeSize(SWT.DEFAULT, SWT.DEFAULT);
getShell()
.setSize(
new Point(windowSize.x, windowSize.y
+ (newSize.y - oldSize.y)));
}