GPX-Viewer improvements

Last few days I have been improving gpx-viewer, a quick list:

• Support multiple maps (cycle map, transport map, etc).
• Fix playback
• Show elevation difference/Gradient.
• Recent File support.
• Distance vs. time graph.
• Docks.

I added docks using libgdl, but having some problems.  If somebody can tell me what I am doing wrong?

Problems I am having: 1. Sometimes the dock when dragged is empty (until docked again). 2. Sometimes widgets in the dock are disappearing.

I do think it is some improvement..

Screenshots: