What does the mouse-binding "in-between move" do? Soo, changed my settings around a bit so that Shift-C is cursor-to-selected and Ctrl-S is "view all without moving cursor". After doing this I had some intermittant trouble with the view resetting with the original Shift-C action when I alt-tabbed or used my screenshot program.

I finally tracked it down today; somehow this got set instead of disabling the original command:



I can't find "In-between Move" anywhere else in the key list; though that might be because search dosen't seem to work on it:



Note that the box dosen't become red like you typed something invalid in it.

Sooo ... what is this mouse action supposed to represent, anyway? I can't consistantly do it, so I'm not positive what it is, but I guess it has something to do with dragging between windows?
This is an event used internally for painting and sculpting tools, it is not useful in a keymap. It can be used when writing certain tools in Python (typically modal operators).

What this event does is give you higher resolution mouse positions in between the regular mouse move events. For most tools only the latest mouse position matters, and processing the positions in between would just be wasting time. But for some tools like painting and sculpting it's useful to known the full path that the mouse traveled to get more accurate paint strokes.