Add mouse binding pointer position configuration

Add mouse binding pointer position configuration

Add the `--whole-window` switch for mouse bindings. This switch controls
what part of the container the pointer must be over to trigger a mouse
binding. The default is to only trigger mouse bindings over the
titlebars. With this switch, a mouse binding will be triggered over the
main part of the window as well.

This is a breaking change to the previous behavior, which would trigger
a mouse binding with a modifier over any part of the window.

fixes #1429