diff --git a/src/Fl_Screen_Driver.H b/src/Fl_Screen_Driver.H
index 511f892d2..05924812c 100644
--- a/src/Fl_Screen_Driver.H
+++ b/src/Fl_Screen_Driver.H
@@ -136,16 +136,17 @@ public:
   // we no longer need the on-screen keyboard; it's up to the system to hide it
   virtual void release_keyboard() { }
 
-  // read raw image from a window or an offscreen buffer
-  /* Member function read_win_rectangle() supports the public function
-   fl_read_image() which captures pixel data either from
-   the current window or from an offscreen buffer.
-
-   With fl_read_image() and for capture from a window, the returned pixel array
-   also contains data from any embedded sub-window.
+  /* Member function read_win_rectangle() supports public functions
+   fl_read_image() and fl_capture_window_part() which capture pixel data from
+   a window (or also from an offscreen buffer with fl_read_image).
    
-   In the case of read_win_rectangle() and for capture from a window, only data
-   from the current window is collected.
+   If 'may_capture_subwins' is true, an implementation may or may not capture
+   also the content of subwindows embedded in 'win'. If subwindows were captured,
+   *'did_capture_subwins' is returned set to true. If read_win_rectangle()
+   is called with 'may_capture_subwins' set to true, 'did_capture_subwins' should
+   be set before the call to the address of a boolean set to false.
+   The implementation of this virtual function for the macOS platform has the
+   capability of capturing subwindows when asked for.
    
    A platform may also use its read_win_rectangle() implementation to capture
    window decorations (e.g., title bar). In that case, it is called by
@@ -153,7 +154,8 @@ public:
    
    win is the window to capture from, or NULL to capture from the current offscreen
    */
-  virtual Fl_RGB_Image *read_win_rectangle(int X, int Y, int w, int h, Fl_Window *win) {return NULL;}
+  virtual Fl_RGB_Image *read_win_rectangle(int X, int Y, int w, int h, Fl_Window *win,
+                                           bool may_capture_subwins = false, bool *did_capture_subwins = NULL) {return NULL;}
   static void write_image_inside(Fl_RGB_Image *to, Fl_RGB_Image *from, int to_x, int to_y);
   static Fl_RGB_Image *traverse_to_gl_subwindows(Fl_Group *g, int x, int y, int w, int h,
                                                  Fl_RGB_Image *full_img);
diff --git a/src/Fl_Screen_Driver.cxx b/src/Fl_Screen_Driver.cxx
index cc54d53cb..c18cd40d3 100644
--- a/src/Fl_Screen_Driver.cxx
+++ b/src/Fl_Screen_Driver.cxx
@@ -190,17 +190,18 @@ Image depths can differ between "to" and "from".
 Fl_RGB_Image *Fl_Screen_Driver::traverse_to_gl_subwindows(Fl_Group *g, int x, int y, int w, int h,
                                                           Fl_RGB_Image *full_img)
 {
+  bool captured_subwin = false;
   if ( g->as_gl_window() ) {
     Fl_Device_Plugin *plugin = Fl_Device_Plugin::opengl_plugin();
     if (!plugin) return full_img;
     full_img = plugin->rectangle_capture(g, x, y, w, h);
   }
   else if ( g->as_window() ) {
-    full_img = Fl::screen_driver()->read_win_rectangle(x, y, w, h, g->as_window());
+    full_img = Fl::screen_driver()->read_win_rectangle(x, y, w, h, g->as_window(), true, &captured_subwin);
   }
   if (!full_img) return NULL;
   float full_img_scale =  (full_img && w > 0 ? float(full_img->data_w())/w : 1);
-  int n = g->children();
+  int n = (captured_subwin ? 0 : g->children());
   for (int i = 0; i < n; i++) {
     Fl_Widget *c = g->child(i);
     if ( !c->visible() || !c->as_group()) continue;
diff --git a/src/Fl_cocoa.mm b/src/Fl_cocoa.mm
index c99d73aab..226d093e3 100644
--- a/src/Fl_cocoa.mm
+++ b/src/Fl_cocoa.mm
@@ -4255,13 +4255,13 @@ static NSBitmapImageRep* rect_to_NSBitmapImageRep(Fl_Window *win, int x, int y,
 #endif
     }
   }
-  if (!bitmap) return nil;
+  if (!capture_subwins || !bitmap) return bitmap;
 
   // capture also subwindows
   NSArray *children = [fl_xid(win) childWindows]; // 10.2
   NSEnumerator *enumerator = [children objectEnumerator];
   id child;
-  while (capture_subwins && ((child = [enumerator nextObject]) != nil)) {
+  while ((child = [enumerator nextObject]) != nil) {
     if (![child isKindOfClass:[FLWindow class]]) continue;
     Fl_Window *sub = [(FLWindow*)child getFl_Window];
     CGRect rsub = CGRectMake(sub->x(), win->h() -(sub->y()+sub->h()), sub->w(), sub->h());
@@ -4272,7 +4272,9 @@ static NSBitmapImageRep* rect_to_NSBitmapImageRep(Fl_Window *win, int x, int y,
                                                              win->h() - clip.origin.y - sub->y() - clip.size.height, clip.size.width, clip.size.height);
     if (childbitmap) {
       // if bitmap is high res and childbitmap is not, childbitmap must be rescaled
-      if ([bitmap pixelsWide] > w && [childbitmap pixelsWide] == clip.size.width) childbitmap = scale_nsbitmapimagerep(childbitmap, 2);
+      if (!win->as_gl_window() && Fl_Cocoa_Window_Driver::driver(win)->mapped_to_retina() && sub->as_gl_window() && !Fl::use_high_res_GL()) {
+        childbitmap = scale_nsbitmapimagerep(childbitmap, 2);
+      }
       write_bitmap_inside(bitmap, w*s, childbitmap,
                           (clip.origin.x - x)*s, (win->h() - clip.origin.y - clip.size.height - y)*s );
     }
diff --git a/src/drivers/Cocoa/Fl_Cocoa_Screen_Driver.H b/src/drivers/Cocoa/Fl_Cocoa_Screen_Driver.H
index 2b329367b..faf5b8520 100644
--- a/src/drivers/Cocoa/Fl_Cocoa_Screen_Driver.H
+++ b/src/drivers/Cocoa/Fl_Cocoa_Screen_Driver.H
@@ -99,7 +99,7 @@ public:
   virtual APP_SCALING_CAPABILITY rescalable() { return SYSTEMWIDE_APP_SCALING; }
   virtual float scale(int n) {return scale_;}
   virtual void scale(int n, float f) { scale_ = f;}
-  virtual Fl_RGB_Image *read_win_rectangle(int X, int Y, int w, int h, Fl_Window *win);
+  virtual Fl_RGB_Image *read_win_rectangle(int X, int Y, int w, int h, Fl_Window *win, bool may_capture_subwins, bool *did_capture_subwins);
 private:
   float scale_;
 };
diff --git a/src/drivers/Cocoa/Fl_Cocoa_Screen_Driver.cxx b/src/drivers/Cocoa/Fl_Cocoa_Screen_Driver.cxx
index d3ec31fdf..34e1c80fd 100644
--- a/src/drivers/Cocoa/Fl_Cocoa_Screen_Driver.cxx
+++ b/src/drivers/Cocoa/Fl_Cocoa_Screen_Driver.cxx
@@ -339,7 +339,8 @@ void Fl_Cocoa_Screen_Driver::offscreen_size(Fl_Offscreen off, int &width, int &h
   height = CGBitmapContextGetHeight(off);
 }
 
-Fl_RGB_Image *Fl_Cocoa_Screen_Driver::read_win_rectangle(int X, int Y, int w, int h, Fl_Window *window)
+Fl_RGB_Image *Fl_Cocoa_Screen_Driver::read_win_rectangle(int X, int Y, int w, int h, Fl_Window *window,
+                                                         bool may_capture_subwins, bool *did_capture_subwins)
 {
   int bpp, bpr, depth = 4;
   uchar *base, *p;
@@ -374,7 +375,8 @@ Fl_RGB_Image *Fl_Cocoa_Screen_Driver::read_win_rectangle(int X, int Y, int w, in
     bpr = 0;
   } else { // read from window
     Fl_Cocoa_Window_Driver *d = Fl_Cocoa_Window_Driver::driver(window);
-    CGImageRef cgimg = d->CGImage_from_window_rect(X, Y, w, h, false);
+    CGImageRef cgimg = d->CGImage_from_window_rect(X, Y, w, h, may_capture_subwins);
+    if (did_capture_subwins) *did_capture_subwins = may_capture_subwins;
     if (!cgimg) {
       return NULL;
     }
diff --git a/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.H b/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.H
index 09beb1108..11a923331 100644
--- a/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.H
+++ b/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.H
@@ -75,7 +75,7 @@ public:
   virtual void remove_timeout(Fl_Timeout_Handler cb, void *argp);
   virtual int dnd(int unused);
   virtual int compose(int &del);
-  virtual Fl_RGB_Image *read_win_rectangle(int X, int Y, int w, int h, Fl_Window *win);
+  virtual Fl_RGB_Image *read_win_rectangle(int X, int Y, int w, int h, Fl_Window *win, bool may_capture_subwins, bool *did_capture_subwins);
   Fl_RGB_Image *read_win_rectangle_unscaled(int X, int Y, int w, int h, Fl_Window *win);
   virtual int get_mouse(int &x, int &y);
   virtual void enable_im();
diff --git a/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx b/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx
index 5eff35d9d..edbfba577 100644
--- a/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx
+++ b/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx
@@ -488,7 +488,8 @@ Fl_WinAPI_Screen_Driver::read_win_rectangle(
                                             int   Y,		// I - Top position
                                             int   w,		// I - Width of area to read
                                             int   h,		// I - Height of area to read
-                                            Fl_Window *win)     // I - window to capture from or NULL to capture from current offscreen
+                                            Fl_Window *win,     // I - window to capture from or NULL to capture from current offscreen
+                                            bool may_capture_subwins, bool *did_capture_subwins)
 {
   float s = Fl_Surface_Device::surface()->driver()->scale();
   int ws, hs;
diff --git a/src/drivers/X11/Fl_X11_Screen_Driver.H b/src/drivers/X11/Fl_X11_Screen_Driver.H
index 7b14d4375..09b043c71 100644
--- a/src/drivers/X11/Fl_X11_Screen_Driver.H
+++ b/src/drivers/X11/Fl_X11_Screen_Driver.H
@@ -95,7 +95,7 @@ public:
   virtual int compose(int &del);
   virtual void compose_reset();
   virtual int text_display_can_leak();
-  virtual Fl_RGB_Image *read_win_rectangle(int X, int Y, int w, int h, Fl_Window *win);
+  virtual Fl_RGB_Image *read_win_rectangle(int X, int Y, int w, int h, Fl_Window *win, bool may_capture_subwins, bool *did_capture_subwins);
   virtual int get_mouse(int &x, int &y);
   virtual void enable_im();
   virtual void disable_im();
diff --git a/src/drivers/X11/Fl_X11_Screen_Driver.cxx b/src/drivers/X11/Fl_X11_Screen_Driver.cxx
index ed703f78d..d13562ea9 100644
--- a/src/drivers/X11/Fl_X11_Screen_Driver.cxx
+++ b/src/drivers/X11/Fl_X11_Screen_Driver.cxx
@@ -745,7 +745,7 @@ extern "C" {
   }
 }
 
-Fl_RGB_Image *Fl_X11_Screen_Driver::read_win_rectangle(int X, int Y, int w, int h, Fl_Window *win)
+Fl_RGB_Image *Fl_X11_Screen_Driver::read_win_rectangle(int X, int Y, int w, int h, Fl_Window *win, bool may_capture_subwins, bool *did_capture_subwins)
 {
   XImage	*image;		// Captured image
   int		i, maxindex;	// Looping vars