Blog Post #0098: More HeaderBar Stuff

[Ron Tarrant via Digitalmars-d-learn]

Wanna know how to rearrange the contents of your HeaderBar? Or 
add extra widgets to that same HeaderBar? Then come on over to 
the GtkD Coding Blog and have a read: 
https://gtkdcoding.com/2020/01/14/0098-headerbar-more.html