Update 2015-06
Based on antoinepairet’s comment/example:
Using uib-collapse attribute provides animations: http://plnkr.co/edit/omyoOxYnCdWJP8ANmTc6?p=preview
<nav class="navbar navbar-default" role="navigation">
<div class="navbar-header">
<!-- note the ng-init and ng-click here: -->
<button type="button" class="navbar-toggle" ng-init="navCollapsed = true" ng-click="navCollapsed = !navCollapsed">
<span class="sr-only">Toggle navigation</span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<a class="navbar-brand" href="#">Brand</a>
</div>
<div class="collapse navbar-collapse" uib-collapse="navCollapsed">
<ul class="nav navbar-nav">
...
</ul>
</div>
</nav>
Ancient..
I see that the question is framed around BS2, but I thought I’d pitch in with a solution for Bootstrap 3 using ng-class solution based on suggestions in ui.bootstrap issue 394:
The only variation from the official bootstrap example is the addition of ng- attributes noted by comments, below:
<nav class="navbar navbar-default" role="navigation">
<div class="navbar-header">
<!-- note the ng-init and ng-click here: -->
<button type="button" class="navbar-toggle" ng-init="navCollapsed = true" ng-click="navCollapsed = !navCollapsed">
<span class="sr-only">Toggle navigation</span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<a class="navbar-brand" href="#">Brand</a>
</div>
<!-- note the ng-class here -->
<div class="collapse navbar-collapse" ng-class="{'in':!navCollapsed}">
<ul class="nav navbar-nav">
...
Here is an updated working example: http://plnkr.co/edit/OlCCnbGlYWeO7Nxwfj5G?p=preview (hat tip Lars)
This seems to works for me in simple use cases, but you’ll note in the example that the second dropdown is cut off.