If a webpage has multiple IFRAME elements that stack into one another, you may have to click an inner input field two times to set the focus on the input field.
This issue occurs in Internet Explorer 11, Internet Explorer 10, Windows Internet Explorer 9, and Windows Internet Explorer 8.
This issue occurs because of an incorrect logic for detecting active elements in the webpage.
To resolve this issue, install the most recent cumulative security update for Internet Explorer. To do this, go to Microsoft Update. Additionally, see the technical information about the most recent cumulative security update for Internet Explorer.
This update was first included in the April 2015 cumulative security update for Internet Explorer (MS15-032).
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
See the terminology that Microsoft uses to describe software updates.