Differential Revision: https://code.wildfiregames.com/D2206 Tested on: clang 8.0.1., Jenkins This was SVN commit r22931.
Finishes GUIutil rewrite and fixes #5575. Differential Revision: https://code.wildfiregames.com/D2233 Test on: clang 8.0.1, Jenkins This was SVN commit r22801.