When an application is built with Qt4, but osgQt was built with Qt5 (or vice versa), upon #includeing osgQt users will receive an #error aborting the build. This at least provides a proper error message rather than a crash, while we are working on better fixes for the problem." git-svn-id: http://svn.openscenegraph.org/osg/OpenSceneGraph/trunk@14918 16af8721-9629-0410-8352-f15c8da7e697