Virtual time control

Goal: control virtual time using a media player like interface (i.e., a timeline, player/pause button, speed control, etc.).

This is currently not possible because the time delta for each frame is sent directly from the window system (at least Qt) to the capability. I would suggest to add a tool in between that implements the functionality mentioned above and a widget to control it.

What do you think?

Start by tracing how the window system, particularly Qt, sends each frame's time delta directly to the capability. Then define the proposed intermediate tool and widget around the media-player interface: timeline, play/pause, and speed control. Done means virtual time can be controlled through these controls instead of being determined only by the window-system frame delta.

Written by the indexing model from the issue text.