Switch between share and pick button depending on web activity

Signed-off-by: Kaustav Das Modak <kaustav.dasmodak@yahoo.co.in>
Make preview and share button handlers check for their existence

Signed-off-by: Kaustav Das Modak <kaustav.dasmodak@yahoo.co.in>
Add handler for pick

Signed-off-by: Kaustav Das Modak <kaustav.dasmodak@yahoo.co.in>