I got the same make error as many folks here did.
For me, the solution to the error (below) was rather cryptic, and probably the reason I had to search with diligence to find this application in the first place. it appears dead, unmaintained, and although I attempted to install all three available versions, they all incurred the same error on three different Linux distros.
Other people who contacted the author stated that he just referred them here to freshmeat for the solution - which again, was cryptic.
Minor edit needed in coollocal.h. Need to add "static " to run_callbacks declaration.
[cooledit-3.17.17]$ vi +52 ./widget/coollocal.h
int eh_picture ...
void drawstring_xy ...
void drawstring_xy_hotkey ...
I used to use this editor way back, and wanted to install and use it again, since I needed something that runs under X, as I use Twin as a window manager.
Oh well, maybe I'll see an actual solution here someday with the actual line as it is supposed to be. It's truly a shame.
I don't understand why this project has fallen off the map, so to speak.
There is no corollary to this product, as it runs nicely on my machines, full screen on a pager screen under KDE or XFCE (nice).
Within Twin itself, I have several windows running, typically w/SSH sessions to other machines I'm managing, where I'll run screen or tmux sessions.
Twin is a remarkable product, the latest release and tutorials/docs for which can be found at the author's website: http://linuz.sns.it/~max/twin
The current release at the time of this writing is 0.6.2
I am so surprised that there aren't several products based upon this software, which had its humble beginnings on <cough, cough> DOS, of all things.