commontk/CTK — pull request #374 by lassoan (2013-10-06 22:35:44+00:00)
Title: 373 - Added check to only grab visible child widgets

Trying to grab a non-visible widget may lead to an application hang, because glGetError may never clear the error if a GL context is not created.
See details at http://www.na-mic.org/Bug/view.php?id=3438