Attempt to improve fl_disable_wayland().

FL/platform.H

@@ -76,5 +76,6 @@ extern FL_EXPORT void fl_close_display();
 extern FL_EXPORT Window fl_window;
 extern FL_EXPORT int fl_parse_color(const char* p, uchar& r, uchar& g, uchar& b);
 extern FL_EXPORT void fl_open_callback(void (*)(const char *));
+extern FL_EXPORT void fl_disable_wayland();
 
 #endif // !FL_PLATFORM_H

FL/wayland.H

@@ -39,10 +39,6 @@ extern FL_EXPORT cairo_t *fl_wl_cairo();
 typedef void *EGLContext;
 /** Returns the EGLContext corresponding to the given GLContext */
 extern FL_EXPORT EGLContext fl_wl_glcontext(GLContext rc);
-/** Prevent the FLTK library from using its wayland backend.
- Call this early in your main(), before fl_open_display() runs. */
-extern FL_EXPORT void fl_disable_wayland();
-
 
 #ifndef FL_DOXYGEN
 

src/Fl.cxx

@@ -2015,6 +2015,15 @@ void fl_close_display()
   Fl::screen_driver()->close_display();
 }
 
+/** Prevent the FLTK library from using its wayland backend.
+ Call this early in your main(), before fl_open_display() runs.
+ This has no effect on non-Wayland platforms.
+ */
+void fl_disable_wayland()
+{
+  Fl::system_driver()->disable_wayland();
+}
+
 FL_EXPORT Window fl_xid_(const Fl_Window *w) {
   Fl_X *temp = Fl_X::i(w);
   return temp ? (Window)temp->xid : 0;

src/Fl_System_Driver.H

@@ -255,6 +255,7 @@ public:
   virtual void unlock_ring() {}
   virtual double wait(double);                             // must override
   virtual int ready() { return 0; }                        // must override
+  virtual void disable_wayland() {}
 };
 
 #endif // FL_SYSTEM_DRIVER_H

src/drivers/Wayland/Fl_Wayland_System_Driver.H

@@ -26,6 +26,7 @@ public:
   int event_key(int k);
   int get_key(int k);
   virtual void *control_maximize_button(void *data);
+  virtual void disable_wayland();
 };
 
 #endif /* FL_WAYLAND_SYSTEM_DRIVER_H */

src/drivers/Wayland/Fl_Wayland_System_Driver.cxx

@@ -88,3 +88,21 @@ void *Fl_Wayland_System_Driver::control_maximize_button(void *data) {
     return NULL;
   }
 }
+
+
+void Fl_Wayland_System_Driver::disable_wayland() {
+  if (fl_wl_display()) {
+    fprintf(stderr, "Error: fl_disable_wayland() cannot be called "
+            "after the Wayland display was opened\n");
+    exit(1);
+  }
+
+  if (Fl_Wayland_Screen_Driver::wl_display) {
+    wl_display_disconnect(Fl_Wayland_Screen_Driver::wl_display);
+    Fl_Wayland_Screen_Driver::wl_display = NULL;
+    delete Fl_Screen_Driver::system_driver;
+    Fl_Screen_Driver::system_driver = NULL;
+  }
+  Fl_Wayland_Screen_Driver::wld_disabled = true;
+  Fl::system_driver();
+}

src/drivers/Wayland/fl_wayland_platform_init.cxx

@@ -35,18 +35,6 @@
 #include <stdio.h>
 
 
-void fl_disable_wayland() {
-  if (Fl_Wayland_Screen_Driver::wl_display) {
-    wl_display_disconnect(Fl_Wayland_Screen_Driver::wl_display);
-    Fl_Wayland_Screen_Driver::wl_display = NULL;
-    delete Fl_Screen_Driver::system_driver;
-    Fl_Screen_Driver::system_driver = NULL;
-  }
-  Fl_Wayland_Screen_Driver::wld_disabled = true;
-  Fl::system_driver();
-}
-
-
 Fl_System_Driver *Fl_System_Driver::newSystemDriver() {
   const char *backend = ::getenv("FLTK_BACKEND");
   const char *xdgrt = ::getenv("XDG_RUNTIME_DIR");