Create struct wld_window *Fl_Wayland_Window_Driver::wld_window to replace eventually fl_window.

src/drivers/Wayland/Fl_Wayland_Copy_Surface_Driver.cxx

@@ -24,7 +24,7 @@
 
 
 Fl_Wayland_Copy_Surface_Driver::Fl_Wayland_Copy_Surface_Driver(int w, int h) : Fl_Copy_Surface_Driver(w, h) {
-  int os_scale = (fl_window ? fl_window->scale : 1);
+  int os_scale = (Fl_Wayland_Window_Driver::wld_window ? Fl_Wayland_Window_Driver::wld_window->scale : 1);
   img_surf = new Fl_Image_Surface(w * os_scale, h * os_scale);
   driver(img_surf->driver());
   driver()->scale(os_scale);

src/drivers/Wayland/Fl_Wayland_Gl_Window_Driver.cxx

@@ -84,10 +84,10 @@ void Fl_Wayland_Gl_Window_Driver::init() {
 char *Fl_Wayland_Gl_Window_Driver::alpha_mask_for_string(const char *str, int n, int w, int h, Fl_Fontsize fs)
 {
   // write str to a bitmap just big enough
-  Window save_win = fl_window;
-  fl_window = NULL;
+  struct wld_window *save_win = Fl_Wayland_Window_Driver::wld_window;
+  fl_window = Fl_Wayland_Window_Driver::wld_window = NULL;
   Fl_Image_Surface *surf = new Fl_Image_Surface(w, h);
-  fl_window = save_win;
+  fl_window = Fl_Wayland_Window_Driver::wld_window = save_win;
   Fl_Font f=fl_font();
   Fl_Surface_Device::push_current(surf);
   fl_color(FL_BLACK);

src/drivers/Wayland/Fl_Wayland_Image_Surface_Driver.H

@@ -22,7 +22,7 @@
 
 class Fl_Wayland_Image_Surface_Driver : public Fl_Image_Surface_Driver {
   virtual void end_current();
-  Window pre_window;
+  struct wld_window *pre_window;
 public:
   Fl_Wayland_Image_Surface_Driver(int w, int h, int high_res, Fl_Offscreen off);
   ~Fl_Wayland_Image_Surface_Driver();

src/drivers/Wayland/Fl_Wayland_Image_Surface_Driver.cxx

@@ -25,8 +25,8 @@ Fl_Wayland_Image_Surface_Driver::Fl_Wayland_Image_Surface_Driver(int w, int h, i
   float d = 1;
   if (!off) {
     fl_open_display();
-    if (fl_window) {
-      d = fl_window->scale;
+    if (Fl_Wayland_Window_Driver::wld_window) {
+      d = Fl_Wayland_Window_Driver::wld_window->scale;
     }
     d *= fl_graphics_driver->scale();
     if (d != 1 && high_res) {
@@ -56,14 +56,14 @@ Fl_Wayland_Image_Surface_Driver::~Fl_Wayland_Image_Surface_Driver() {
 void Fl_Wayland_Image_Surface_Driver::set_current() {
   Fl_Surface_Device::set_current();
   ((Fl_Wayland_Graphics_Driver*)fl_graphics_driver)->activate(offscreen, driver()->scale());
-  pre_window = fl_window;
-  fl_window = NULL;
+  pre_window = Fl_Wayland_Window_Driver::wld_window;
+  fl_window = Fl_Wayland_Window_Driver::wld_window = NULL;
 }
 
 void Fl_Wayland_Image_Surface_Driver::end_current() {
   cairo_surface_t *surf = cairo_get_target(offscreen->cairo_);
   cairo_surface_flush(surf);
-  fl_window = pre_window;
+  fl_window = Fl_Wayland_Window_Driver::wld_window = pre_window;
 }
 
 void Fl_Wayland_Image_Surface_Driver::translate(int x, int y) {

src/drivers/Wayland/Fl_Wayland_Window_Driver.H

@@ -88,6 +88,7 @@ public:
   struct xdg_toplevel *xdg_toplevel();
   Fl_Wayland_Window_Driver(Fl_Window*);
   virtual ~Fl_Wayland_Window_Driver();
+  static struct wld_window *wld_window;
   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);}

src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx

@@ -52,6 +52,7 @@ extern "C" {
 #define fl_max(a,b) ((a) > (b) ? (a) : (b))
 
 Window fl_window;
+struct wld_window *Fl_Wayland_Window_Driver::wld_window = NULL;
 
 
 void Fl_Wayland_Window_Driver::destroy_double_buffer() {
@@ -405,7 +406,7 @@ void Fl_Wayland_Window_Driver::make_current() {
   }
 
   fl_graphics_driver->clip_region(0);
-  fl_window = window;
+  fl_window = Fl_Wayland_Window_Driver::wld_window = window;
   if (!window->buffer) {
     window->buffer = Fl_Wayland_Graphics_Driver::create_shm_buffer(
            pWindow->w() * scale, pWindow->h() * scale);