The windows actually open to the appropriate dimensions, so there isn't blank space unless they maximize the window.
We may be able to develop a custom theme with adaptive size, but the cost might be prohibitive, and you would lose the consistency of the look and feel. The drawback with using a templated system such as ours is that the templates tend to be rigid in terms of element positioning and size in order to provide a consistent look and feel. The advantage, of course, is the speed with which you can develop your eLearning material.
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