@hg2581 what does `pkg-config --modversion geany` tells you? and if it says it doesn't find any packages like this, check whether you have a file named *geany.pc* somewhere, likely in */usr/lib/pkgconfig* or */usr/local/lib/pkgconfig*. If you don't have this file anywhere on your system, then the development files for Geany aren't properly installed.
BTW, I could imagine your distro having something like *geany-devel*, *geany-libgeany-1.26-devel* or alike, in which case you should install it to get the appropriate development files.
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