Incorrect selection duration in status bar

[bartekmotyl]

Replication procedure:

• open a video file
• select a portion of video, preferably short one towards end of video
• selection duration shown in status bar is incorrect

Additionally, duration is not updated when selections are modified by drag & drop.

Expected:

• duration shown in status bar is a sum of durations of all selections, updated on every change ("live")

[bartekmotyl]

Fixed in development branch, will be included in v0.23