It's still there and working in 3.7. The sample doesn't seem to work for an unrelated reason. If you are using AMD you need to require dojox/layout/Dock. The legacy floating pane require loaded the dock module.AMD:require([
'dojox/layout/FloatingPane',
'dojox/layout/Dock',
'dojo/dom-construct',
'dojo/_base/window'
], function (FloatingPane, Dock, domConstruct, win) {
var dock = new Dock({
//params
}, domConstruct.create('div', null, win.body()));
var fp = new FloatingPane({
//params
dockTo: dock
}, domConstruct.create('div', null, win.body()));
fp.startup();
});