Possible fix for the window focus issue on macOS
Possible fix for the window focus issue on macOS

as reported by @dgbeecher

Glutanimate/image-occlusion-2-enhanced,Glutanimate/image-occlusion-enhanced,Glutanimate/image-occlusion-2-enhanced,Glutanimate/image-occlusion-2-enhanced,Glutanimate/image-occlusion-enhanced,Glutanimate/image-occlusion-2-enhanced,Glutanimate/image-occlusion-2-enhanced