Allow for image saving after pausing bag file

[Chambana]

When my bag file is playing, I can easily click the "Save" icon and write the current frame from my streaming camera feed to disk. However, when I pause my bag file playback to grab a specific image, the "Save" icon no longer functions and I can't save the paused image being displayed in the window. Unless I'm doing something wrong, this is a feature request. Thanks.

How I'm executing the node: rosrun image_view image_view image:=/usb_cam/image_raw compressed _autosize:=true

Using ROS Kinetic on Ubuntu 16.04.3 LTS

[SteveMacenski]

PRs welcome

[mikeferguson]

Kinetic is EOL, not sure if this is an issue on more recent versions