Allow rolling inside clips (move the in_point but don't change start position and duration)
@weldjuggling
Submitted by DELETED Assigned to DELETED @weldjuggling
Description
When pressing the Ctrl key, clicking in the middle of a clip and dragging it to the right or to the left, the in_point of the clip will be changed, while its start position in the timeline and the duration stay the same:
[ A ][345][ C ] ==(Ctrl + drag [345] rightwards)==> [ A ][123][ C ]
[ A ][345][ C ] ==(Ctrl + drag [345] leftwards)===> [ A ][567][ C ]
Imported from https://bugzilla.gnome.org/show_bug.cgi?id=625691