The patch adds an "Handle" option to the SEQUENCER_OT_box_select operator, that allows to select the handles instead of whole strips.
I mapped this to Alt+B, so that I could also consistently use the Alt modifier for the mouse tweak shortcuts (I guess this would need to be better addressed when the active tools gets implemented in the vse, but for the moment this seemed a good solution to me).
A difference from the proposed design in T70730 is that covering the entire strip with the box actually selects both handles; testing this I found that it did make more sense to me to keep the two behaviours more distinct.
At the moment, when the box covers one handle, the behaviour is the following:
- Select -> Strip and handle get selected
- Deselect, strip selected with no handles selected -> The opposite handle get selected (left one in the example)
- Deselect, both handles selected -> Handle get deselected
- Deselect, strip selected, covered handle is the only one selected -> Both the strip and the handle get deselected
When the box covers the entire strip everything get (de)selected.
Regular box selection now also deselect the handles.