What are normal and timing mode?
In VSS, there are two modes available: the normal mode and the timing mode. Both modes have a different configurable (Edit > Preferences > HotKeys) set of hotkeys. In timing mode you can change (Edit > Preferences > Mouse) the behavior of the mouse to use a SubStation Alpha like mouse mode: Left/right mouse button set start/stop time. You can also use the space key to create or modify (Edit > Preferences > General > Misc) subtitles with just one key by pressing it when subtitle start, then releasing it when subtitle stop.