Simplify Fl_Window_Driver::screen_num() member functions.

src/Fl_Window_Driver.H

@@ -43,7 +43,7 @@ class Fl_RGB_Image;
 
  This class is only for internal use by the FLTK library.
 
- When porting FLTK to a new platform, many mothods in this class provide
+ When porting FLTK to a new platform, many methods in this class provide
  a minimal default implementation. Some methods must be overridden to make
  sure that the Graphics Driver will draw into the bitmap associated with
  this window.
@@ -56,6 +56,7 @@ private:
 
 protected:
   Fl_Window *pWindow;
+  int screen_num_; // number of screen where window is mapped
   void flush_Fl_Window(); // accessor to protected Fl_Window::flush()
 public:
   Fl_Window_Driver(Fl_Window *);
@@ -65,8 +66,8 @@ public:
   static Fl_Window *find(fl_uintptr_t xid);
   int wait_for_expose_value;
   Fl_Offscreen other_xid; // offscreen bitmap (overlay and double-buffered windows)
-  virtual int screen_num();
-  virtual void screen_num(int) {}
+  int screen_num();
+  void screen_num(int n) { screen_num_ = n; }
 
 
   // --- frequently used accessors to public window data

src/Fl_Window_Driver.cxx

@@ -41,6 +41,7 @@ Fl_Window_Driver::Fl_Window_Driver(Fl_Window *win)
   : pWindow(win) {
   wait_for_expose_value = 0;
   other_xid = 0;
+  screen_num_ = 0;
 }
 
 
@@ -219,8 +220,10 @@ void Fl_Window_Driver::wait_for_expose() {
 }
 
 int Fl_Window_Driver::screen_num() {
-  if (pWindow->parent()) return Fl_Window_Driver::driver(pWindow->top_window())->screen_num();
-  return Fl::screen_num(x(), y(), w(), h());
+  if (pWindow->parent()) {
+    screen_num_ = Fl_Window_Driver::driver(pWindow->top_window())->screen_num();
+  }
+  return screen_num_ >= 0 ? screen_num_ : 0;
 }
 
 bool Fl_Window_Driver::is_a_rescale_ = false;

src/Fl_x.cxx

@@ -2047,6 +2047,8 @@ int fl_handle(const XEvent& thisevent)
       }
       wd->screen_num(num);
     }
+#else // ! USE_XFT
+    Fl_Window_Driver::driver(window)->screen_num( Fl::screen_num(X, Y, W, H) );
 #endif // USE_XFT
 
     // tell Fl_Window about it and set flag to prevent echoing:

src/drivers/Cocoa/Fl_Cocoa_Window_Driver.H

@@ -85,7 +85,6 @@ private:
   // stores 3 binary flags: whether window is mapped to retina display; whether resolution just changed;
   // whether window's view received the [FLView view_did_resize] message
   unsigned window_flags_;
-  int screen_num_; // number of screen where window is mapped
 public:
   Fl_Cocoa_Window_Driver(Fl_Window*);
   ~Fl_Cocoa_Window_Driver();
@@ -134,8 +133,6 @@ public:
   virtual void size_range();
   virtual void iconize();
   virtual void decoration_sizes(int *top, int *left,  int *right, int *bottom);
-  virtual int screen_num();
-  virtual void screen_num(int n);
   // --- window cursor stuff
   virtual int set_cursor(Fl_Cursor);
   virtual int set_cursor(const Fl_RGB_Image*, int, int);

src/drivers/Cocoa/Fl_Cocoa_Window_Driver.cxx

@@ -330,15 +330,6 @@ void Fl_Cocoa_Window_Driver::capture_titlebar_and_borders(Fl_RGB_Image*& top, Fl
   CGContextRelease(auxgc);
 }
 
-void Fl_Cocoa_Window_Driver::screen_num(int n) {
-  screen_num_ = n;
-}
-
-int Fl_Cocoa_Window_Driver::screen_num() {
-  if (pWindow->parent()) return pWindow->top_window()->screen_num();
-  else return screen_num_;
-}
-
 
 FLWindow *fl_mac_xid(const Fl_Window *win) {
   return (FLWindow*)Fl_Window_Driver::xid(win);

src/drivers/Wayland/Fl_Wayland_Window_Driver.H

@@ -74,8 +74,6 @@ public:
     bool busy;
   };
   static type_for_resize_window_between_screens data_for_resize_window_between_screens_;
-  int screen_num_;
-  void screen_num(int n) { screen_num_ = n; }
   void decorated_win_size(int &w, int &h);
   void shape_bitmap_(Fl_Image* b);
   void shape_alpha_(Fl_Image* img, int offset);
@@ -88,7 +86,6 @@ public:
   static void redraw(struct wld_window *window);
 
   static inline Fl_Wayland_Window_Driver* driver(const Fl_Window *w) {return (Fl_Wayland_Window_Driver*)Fl_Window_Driver::driver(w);}
-  virtual int screen_num();
   static void resize_after_screen_change(void *data);
 
   // --- window data

src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx

@@ -1123,14 +1123,6 @@ void Fl_Wayland_Window_Driver::resize_after_screen_change(void *data) {
 }
 
 
-int Fl_Wayland_Window_Driver::screen_num() {
-  if (pWindow->parent()) {
-    screen_num_ = Fl_Window_Driver::driver(pWindow->top_window())->screen_num();
-  }
-  return screen_num_ >= 0 ? screen_num_ : 0;
-}
-
-
 int Fl_Wayland_Window_Driver::set_cursor(Fl_Cursor c) {
   Fl_Wayland_Screen_Driver *scr_driver = (Fl_Wayland_Screen_Driver*)Fl::screen_driver();
 

src/drivers/WinAPI/Fl_WinAPI_Window_Driver.H

@@ -58,7 +58,6 @@ class Fl_WinAPI_Window_Driver : public Fl_Window_Driver
     Fl_Image* shape_; ///<  shape image
     Fl_Bitmap *effective_bitmap_; ///<  auxiliary bitmap image
   } *shape_data_;
-  int screen_num_;
 private:
   void shape_bitmap_(Fl_Image* b);
   void shape_alpha_(Fl_Image* img, int offset);
@@ -68,8 +67,6 @@ public:
   static inline Fl_WinAPI_Window_Driver* driver(const Fl_Window *w) {return (Fl_WinAPI_Window_Driver*)Fl_Window_Driver::driver(w);}
   HDC private_dc; // used for OpenGL
   RECT border_width_title_bar_height(int &bx, int &by, int &bt);
-  virtual void screen_num(int n);
-  virtual int screen_num();
 
   struct icon_data *icon_;
   HCURSOR cursor;

src/drivers/WinAPI/Fl_WinAPI_Window_Driver.cxx

@@ -55,20 +55,9 @@ Fl_WinAPI_Window_Driver::~Fl_WinAPI_Window_Driver()
   delete icon_;
 }
 
-int Fl_WinAPI_Window_Driver::screen_num() {
-  if (pWindow->parent()) {
-    screen_num_ = Fl_Window_Driver::driver(pWindow->top_window())->screen_num();
-  }
-  return screen_num_ >= 0 ? screen_num_ : 0;
-}
 
 //FILE*LOG=fopen("log.log","w");
 
-void Fl_WinAPI_Window_Driver::screen_num(int n) {
-//fprintf(LOG, "screen_num setter old=%d new=%d\n",screen_num_, n);fflush(LOG);
-  screen_num_ = n;
-}
-
 
 RECT // frame of the decorated window in screen coordinates
   Fl_WinAPI_Window_Driver::border_width_title_bar_height(

src/drivers/X11/Fl_X11_Window_Driver.H

@@ -73,8 +73,6 @@ private:
     bool busy;
   };
   static type_for_resize_window_between_screens data_for_resize_window_between_screens_;
-  int screen_num_;
-  void screen_num(int n) { screen_num_ = n; }
 #endif // USE_XFT
 #if FLTK_USE_CAIRO
   cairo_t *cairo_;
@@ -92,7 +90,6 @@ public:
   virtual ~Fl_X11_Window_Driver();
   static inline Fl_X11_Window_Driver* driver(const Fl_Window *w) {return (Fl_X11_Window_Driver*)Fl_Window_Driver::driver(w);}
 #if  USE_XFT
-  virtual int screen_num();
   static void resize_after_screen_change(void *data);
 #endif // USE_XFT
 

src/drivers/X11/Fl_X11_Window_Driver.cxx

@@ -572,14 +572,6 @@ void Fl_X11_Window_Driver::resize_after_screen_change(void *data) {
   data_for_resize_window_between_screens_.busy = false;
 }
 
-
-int Fl_X11_Window_Driver::screen_num() {
-  if (pWindow->parent()) {
-    screen_num_ = Fl_Window_Driver::driver(pWindow->top_window())->screen_num();
-  }
-  return screen_num_ >= 0 ? screen_num_ : 0;
-}
-
 #endif // USE_XFT
 
 fl_uintptr_t Fl_X11_Window_Driver::os_id() {