It would be interesting to know which features you enjoy most. Perhaps gproject already offers them or can be extended.
1) Multi projects opened in a single instance of Geany
2) Setting up a new project is more straightforward :
- Download a tarball -> open a file on the root -> click menu : tools->project->create a project -> enter and you're set up to browse the source code.
- With Gproject, one have to walk the directories to set the base of the project (even if one of its files is already opened), and then set up wildcards (ok I'm a lazy person ;)
Point 2 would be a simple improvement I guess, but point 1 would expect much more dev :(
Gproject is anyway better and more polished, I admit.
Best Regards Johann