--- makefile.orig	2021-04-06 13:42:27 UTC
+++ makefile
@@ -8,22 +8,22 @@ PROJ=fxt
 include flags.mk
 
 #### choose the FLAG combo here:
-FXT_CXXFLAGS=
+#FXT_CXXFLAGS=
 #FXT_CXXFLAGS += -std=c++11
-FXT_CXXFLAGS += -std=c++17
-FXT_CXXFLAGS += -pipe
+#FXT_CXXFLAGS += -std=c++17
+#FXT_CXXFLAGS += -pipe
 #FXT_CXXFLAGS += -fno-exceptions
-FXT_CXXFLAGS += $(OFLAGS) # uncomment for OPTIMIZATION
+#FXT_CXXFLAGS += $(OFLAGS) # uncomment for OPTIMIZATION
 #FXT_CXXFLAGS += -O3 # test -O3
 #FXT_CXXFLAGS += $(GFLAGS) # uncomment for DEBUGGING
 #FXT_CXXFLAGS += $(PFLAGS) # uncomment for PROFILING
 #
-FXT_CXXFLAGS += $(WFLAGS) # uncomment for WARNINGS
+#FXT_CXXFLAGS += $(WFLAGS) # uncomment for WARNINGS
 #FXT_CXXFLAGS += -Werror # make all warnings ERRORS
 #FXT_CXXFLAGS += -fmax-errors=1 # clang chokes on this one
 
 #FXT_CXXFLAGS += -D__NO_MATH_INLINES
-FXT_CXXFLAGS += $(FXT_EXTRA_FLAGS)
+#FXT_CXXFLAGS += $(FXT_EXTRA_FLAGS)
 
 #FXT_CXXFLAGS += $(CLANG_FLAGS)  ## for clang++
 
@@ -200,27 +200,27 @@ install: lib
 	: '[$@]'
 	@echo 'PREFIX=$(PREFIX)  LIBDIR=$(LIBDIR)  INCDIR=$(INCDIR)'
 	@:
-	@test -d $(INCDIR)  ||  mkdir $(INCDIR)
-	@$(FXT_INSTALL) $(FXTIDIR)/*.h $(INCDIR)/
-	@cd src && for f in $(SHFXTSRCDIRS); do mkdir -p $(INCDIR)/$$f; done
-	@cd src && for f in $(SHFXTSRCDIRS); do $(FXT_INSTALL) $$f/*.h $(INCDIR)/$$f; done
+	@test -d $(DESTDIR)$(INCDIR)  ||  mkdir $(DESTDIR)$(INCDIR)
+	@$(FXT_INSTALL) $(FXTIDIR)/*.h $(DESTDIR)$(INCDIR)/
+	@cd src && for f in $(SHFXTSRCDIRS); do mkdir -p $(DESTDIR)$(INCDIR)/$$f; done
+	@cd src && for f in $(SHFXTSRCDIRS); do $(FXT_INSTALL) $$f/*.h $(DESTDIR)$(INCDIR)/$$f; done
 	@:
-	@test -d $(LIBDIR)  ||  mkdir $(LIBDIR)
-	@$(FXT_INSTALL) $(FXTLIB) $(LIBDIR)/
+	@test -d $(DESTDIR)$(LIBDIR)  ||  mkdir $(DESTDIR)$(LIBDIR)
+	@$(FXT_INSTALL) $(FXTLIB) $(DESTDIR)$(LIBDIR)/
 	: '[$@ OK]'
 
 .PHONY: chk-install ##x print whether installed header files are up to date
 chk-install:
 	@(cd src  &&  find . -maxdepth 2 -name \*.h | sort) > tmp-hdr1
-	@(cd $(INCDIR)/  &&  find . -name \*.h | sort) > tmp-hdr2
+	@(cd $(DESTDIR)$(INCDIR)/  &&  find . -name \*.h | sort) > tmp-hdr2
 	@-diff tmp-hdr1 tmp-hdr2
 	@rm tmp-hdr1 tmp-hdr2
 
-.PHONY: uninstall  ## uninstall headers and lib, but leave directory $(INCDIR)
+.PHONY: uninstall  ## uninstall headers and lib, but leave directory $(DESTDIR)$(INCDIR)
 uninstall:
-	: '[$@]'  ## note: we do not remove $(INCDIR)
-	rm -rf $(INCDIR)/*
-	rm -f $(LIBDIR)/$(FXTLIB)
+	: '[$@]'  ## note: we do not remove $(DESTDIR)$(INCDIR)
+	rm -rf $(DESTDIR)$(INCDIR)/*
+	rm -f $(DESTDIR)$(LIBDIR)/$(FXTLIB)
 
 .PHONY: reinstall  ## uninstall and install
 reinstall: # uninstall install
@@ -785,7 +785,7 @@ showsrc:
 #	@for h in */*.h; do \
 # grep -L $$h depend.mk &>/dev/null || echo $$h ; done
 #
-##	@for h in $$(ls -1 $(INCDIR) ); do \
+##	@for h in $$(ls -1 $(DESTDIR)$(INCDIR) ); do \
 
 #.PHONY: shownotes ##x show comments that contain the string "note"
 #shownotes: