In working on fixing a bug today, I made a proposed change or two to graph_analysis.c. See https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=7418 for the context. The first patch was a very conservative one that simply added a bit of code to address a problem with not being able to resize the panes. The second, superseding patch is a bit more extensive in that it completely eliminates the pane_callback function. I thought that I would point out that I have only tested the change on GTK+ 3 and not earlier versions, but didn't know how far back we're intending to support. Comments, accolades, brickbats welcome. :)
Ed