All windows are still draggable using their headers, except for Firefox. Firefox lost its window decorations and can be neither dragged nor resized.
Is it possible to restart a window manager and/or to check its logs?
On my install (Freya) the default key for this functionality is actually Super (meta/windows key). You can change this in dconf-editor by navigating to
org.gnome.desktop.wm.preferences and setting
Gala (Window Manager)
The command to respawn the window manager is
DISPLAY=:0 gala --replace &.
Note that you should do this from a VT (Ctrl+Alt+F1) rather than a gui terminal so the gala process doesn't end when you close said terminal.