<p dir="auto">I found this problem when i try default navbar in <a href="http://getbootstrap.com/components/#navbar-default" rel="nofollow">http://getbootstrap.com/components/#navbar-default</a></p>
<p dir="auto">i resized window to small to make navbar collapsed. and then i open collapsed navbar click the dropdown menu to show sub menu of dropdown and close it. then i resized window to maximum scale and click dropdown menu again it not show sub menu.</p>
<p dir="auto">The default navbar (<a href="http://getbootstrap.com/components/#navbar" rel="nofollow">http://getbootstrap.com/components/#navbar</a>) act a little bit weird when : I click dropdown (keep it opened) and then resize the browser until the navbar-toggle button appear, click it, open the dropdown and then maximize the browser. after those step, I can't open the dropdown on navbar default state..</p>