Steps to reproduce:
1. Open, compile and run the attached project.
2. Press the full-screen button "Toggle toolbar". Observe how the header and footer hide and the button correctly expands into the newly-freed space.
3. Open main.qml and comment out the lines 37 and 38.
4. Re-run the project, click the button and observe that the toolbars do hide but the button is not expanded into the free space.