there have been some problems with the current installation image of Geany 1.29 for OS X which caused it couldn't be started on older OS X versions - for more info, see
I've just re-built and re-uploaded a new image that should fix the problem. You can get it at the usual place here:
There have been no other changes so if everything worked for you, there's no need to download this version.
A bonus feature of this build is that it should run on OS X as old as 10.6.