This patch is exposing the existing Transform Expand mode:
{F9559830,size=full}
As a select/box-select tool toggle button:
{F9559827,size=full}
The reason for this patch is that currently this essential function is that unexposed that even seasoned VSE users are not aware of the expand/ripple mode when transforming, and it is annoying to have to add shortcut-key press for a mode, most users will want to be in most of the time. Since it is implemented as an option in the select/select-box tool, no other tools should are affected or should be.
If this patch gets committed, then this patch(which includes more functionality) can be closed: D9699
EDIT:
Expose it like a boolean: `[ ] Ripple Edit`.
{F9560337}