diff --git a/src/Fl_Window_Driver.cxx b/src/Fl_Window_Driver.cxx
index b16435dcf..11ffb69fe 100644
--- a/src/Fl_Window_Driver.cxx
+++ b/src/Fl_Window_Driver.cxx
@@ -262,15 +262,23 @@ bool Fl_Window_Driver::is_a_rescale_ = false;
 void Fl_Window_Driver::resize_after_scale_change(int ns, float old_f, float new_f) {
   screen_num(ns);
   Fl_Graphics_Driver::default_driver().scale(new_f);
+  int X = pWindow->x()*old_f/new_f, Y = pWindow->y()*old_f/new_f;
   int W, H;
   if (pWindow->fullscreen_active()) {
     W = pWindow->w() * old_f/new_f; H = pWindow->h() * old_f/new_f;
   } else {
     W = pWindow->w(); H = pWindow->h();
+    int sX, sY, sW, sH;
+    Fl::screen_xywh(sX, sY, sW, sH, ns); // bounding box of new screen
+    const int d = 5; // make sure new window centre is located in new screen
+    if (X+W/2 < sX) X = sX-W/2+d;
+    else if (X+W/2 > sX+sW-1) X = sX+sW-1-W/2-d;
+    if (Y+H/2 < sY) Y = sY-H/2+d;
+    else if (Y+H/2 > sY+sH-1) Y = sY+sH-1-H/2-d;
   }
   is_a_rescale_ = true;
   size_range();
-  pWindow->resize(pWindow->x()*old_f/new_f,  pWindow->y()*old_f/new_f, W, H);
+  pWindow->resize(X, Y, W, H);
   is_a_rescale_ = false;
 }
 
diff --git a/src/Fl_win32.cxx b/src/Fl_win32.cxx
index cc58336b1..ebca3c57d 100644
--- a/src/Fl_win32.cxx
+++ b/src/Fl_win32.cxx
@@ -586,7 +586,8 @@ int Fl_WinAPI_Screen_Driver::get_mouse_unscaled(int &mx, int &my) {
   POINT p;
   GetCursorPos(&p);
   mx = p.x; my = p.y;
-  return screen_num_unscaled(mx, my);
+  int screen = screen_num_unscaled(mx, my);
+  return screen >= 0 ? screen : 0;
 }
 
 int Fl_WinAPI_Screen_Driver::get_mouse(int &x, int &y) {
@@ -1460,11 +1461,12 @@ static LRESULT CALLBACK WndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lPar
     if (nx & 0x8000) nx -= 65536;
     if (ny & 0x8000) ny -= 65536;
 //fprintf(LOG,"WM_MOVE position(%d,%d) s=%.2f\n",int(nx/scale),int(ny/scale),scale);
-// detect when window changes screen
+// detect when window centre changes screen
     Fl_WinAPI_Screen_Driver *sd = (Fl_WinAPI_Screen_Driver*)Fl::screen_driver();
-    int news = sd->screen_num_unscaled(nx + window->w()*scale/2, ny + window->h()*scale/2);
     Fl_WinAPI_Window_Driver *wd = Fl_WinAPI_Window_Driver::driver(window);
     int olds = wd->screen_num();
+    int news = sd->screen_num_unscaled(nx + window->w()*scale/2, ny + window->h()*scale/2);
+    if (news == -1) news = olds;
     float s = sd->scale(news);
 //fprintf(LOG,"WM_MOVE olds=%d(%.2f) news=%d(%.2f) busy=%d\n",olds, sd->scale(olds),news, s, Fl_WinAPI_Window_Driver::data_for_resize_window_between_screens_.busy);fflush(LOG);
     if (olds != news) {
diff --git a/src/Fl_x.cxx b/src/Fl_x.cxx
index 25ae92d55..9e51e7068 100644
--- a/src/Fl_x.cxx
+++ b/src/Fl_x.cxx
@@ -726,7 +726,8 @@ int Fl_X11_Screen_Driver::get_mouse_unscaled(int &mx, int &my) {
   Window c; int cx,cy; unsigned int mask;
   XQueryPointer(fl_display, root, &root, &c, &mx, &my, &cx, &cy, &mask);
 #if USE_XFT
-  return screen_num_unscaled(mx, my);
+  int screen = screen_num_unscaled(mx, my);
+  return screen >= 0 ? screen : 0;
 #else
   return screen_num(mx, my);
 #endif
@@ -2015,12 +2016,12 @@ fprintf(stderr,"\n");*/
     Window cr; int X, Y, W = actual.width, H = actual.height;
     XTranslateCoordinates(fl_display, fl_xid(window), actual.root,
                           0, 0, &X, &Y, &cr);
-#if USE_XFT // detect when window changes screen
-    int num = 0;
+#if USE_XFT // detect when window centre changes screen
     Fl_X11_Screen_Driver *d = (Fl_X11_Screen_Driver*)Fl::screen_driver();
-    num = d->screen_num_unscaled(X, Y, actual.width, actual.height);
     Fl_X11_Window_Driver *wd = Fl_X11_Window_Driver::driver(window);
     int olds = wd->screen_num();
+    int num = d->screen_num_unscaled(X+ actual.width/2, Y +actual.height/2);
+    if (num == -1) num = olds;
     float s = d->scale(num);
     if (num != olds) {
       if (s != d->scale(olds) &&
diff --git a/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx b/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx
index 0f0609bcc..1b9b03f17 100644
--- a/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx
+++ b/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx
@@ -666,9 +666,10 @@ void Fl_WinAPI_Screen_Driver::offscreen_size(Fl_Offscreen off, int &width, int &
   }
 }
 
+//NOTICE: returns -1 if x,y is not in any screen
 int Fl_WinAPI_Screen_Driver::screen_num_unscaled(int x, int y)
 {
-  int screen = 0;
+  int screen = -1;
   if (num_screens < 0) init();
   for (int i = 0; i < num_screens; i ++) {
     if (x >= screens[i].left && x < screens[i].right &&
diff --git a/src/drivers/X11/Fl_X11_Screen_Driver.H b/src/drivers/X11/Fl_X11_Screen_Driver.H
index db986b33c..6ceca775c 100644
--- a/src/drivers/X11/Fl_X11_Screen_Driver.H
+++ b/src/drivers/X11/Fl_X11_Screen_Driver.H
@@ -56,7 +56,6 @@ public:
   virtual void scale(int n, float f) { screens[n].scale = f;}
   virtual float desktop_scale_factor();
   int screen_num_unscaled(int x, int y);
-  int screen_num_unscaled(int x, int y, int w, int h);
 #endif
   
   static int ewmh_supported();
diff --git a/src/drivers/X11/Fl_X11_Screen_Driver.cxx b/src/drivers/X11/Fl_X11_Screen_Driver.cxx
index d1390e862..013ae7566 100644
--- a/src/drivers/X11/Fl_X11_Screen_Driver.cxx
+++ b/src/drivers/X11/Fl_X11_Screen_Driver.cxx
@@ -1182,9 +1182,10 @@ void Fl_X11_Screen_Driver::offscreen_size(Fl_Offscreen off, int &width, int &hei
 }
 
 #if USE_XFT
+//NOTICE: returns -1 if x,y is not in any screen
 int Fl_X11_Screen_Driver::screen_num_unscaled(int x, int y)
 {
-  int screen = 0;
+  int screen = -1;
   if (num_screens < 0) init();
   
   for (int i = 0; i < num_screens; i ++) {
@@ -1197,25 +1198,6 @@ int Fl_X11_Screen_Driver::screen_num_unscaled(int x, int y)
   return screen;
 }
 
-int Fl_X11_Screen_Driver::screen_num_unscaled(int x, int y, int w, int h)
-{
-  int best_screen = 0;
-  float best_intersection = 0.;
-  if (num_screens < 0) init();
-  for (int i = 0; i < num_screens; i++) {
-    float sintersection = fl_intersection(x, y, w, h, screens[i].x_org, screens[i].y_org,
-                                          screens[i].width, screens[i].height);
-    if (sintersection > best_intersection) {
-      best_screen = i;
-      best_intersection = sintersection;
-    }
-  }
-  return best_screen;
-}
-#endif
-
-#if USE_XFT
-
 #if HAVE_DLSYM && HAVE_DLFCN_H
 
 // returns true when schema is among the list of available schemas
@@ -1404,8 +1386,6 @@ float Fl_X11_Screen_Driver::desktop_scale_factor()
 }
 
 
-
-
 #endif // USE_XFT
 
 //