Use a central header.

$ time (make clean; make)

Before: ~8.0 seconds
After: ~8.1 seconds

src/ld-window-main.c

@@ -10,21 +10,11 @@
 
 #include <gtk/gtk.h>
 
+#include "liblogdiag.h"
 #include "config.h"
 
 #include "ld-window-main.h"
 
-#include "ld-types.h"
-#include "ld-symbol.h"
-#include "ld-symbol-category.h"
-#include "ld-library.h"
-
-#include "ld-diagram-object.h"
-#include "ld-diagram-symbol.h"
-#include "ld-diagram.h"
-
-#include "ld-canvas.h"
-
 
 /**
  * SECTION:ld-window-main