int hh = 0;
for (int i = 0, len = getWidgetCount(); i < len; i++) {
ContentPanel c = (ContentPanel) getWidget(i);
if (c != activeWidget) {
c.collapse();
hh += c.getAppearance().getHeaderSize(c.getElement()).getHeight();
applyLayout(c, size.getWidth(), -1);
}
}
activeWidget.setPixelSize(size.getWidth(), size.getHeight() - hh);